PHOTOGRAPHERS from a glossy trivia magazine brought along a plastic bloody hand for Tom Lehrer to pose with.

He winces at the recollection.

They couldn't understand, he says plaintively, why he wouldn't do it. In fact he was frankly appalled at the very idea.

In race performance or on his still briskly selling records, Tom Lehrer, the math professor turned underground troubadour (in the '50s and '60s), is all bleak and evil and snide and ever so wicked. When his lyrical characters aren't serving baby brothers up in Irish stews, cherishing severed hands or poisoning pigeons, they are, one way or another, pointing up (and putting down) all the foibles of humanity, especially American humanity. Tom Lehrer exposes the underside and lo! it is hilarious.

Tom Lehrer does not seem like the type to poison pigeons in the park. Of course, the fact that he wasn't immune to the thought is forever engraved on one or another polyvinyl disc, as in: "... But it's not against any religion/To want to dispose of a pigeon..."

In person Lehrer is gentle ("I don't even like movies with hitting, let alone killing,") and diffident. But inevitably mischievous. And the one he puts down the most is himself. As in:

"You know, Mr. Lehrer, my kids grew up on your stuff."

"Oh, sorry to hear that, but they're all right now?"

Lehrer is mildly surprised that he -- his material, anyway -- is staging a comeback. Almost worldwise, at that.

The Arena Stage version of "Tomfoolery" opens Thursday. Another company is performing in New York. A Canadian Company is touring. A South African run has just ended. Another company performed in Australia and the first version was in London.

"Tomfoolery" is the brainchild of Cameron Mackintosh, the British producer who dreamed up the wildly successful "Side by Side by Sondheim." Mackintosh convinced Lehrer to give it a try. With very few revisions, mostly where allusions were too clouded by time, and some lyric polishing by Lehrer, Mackintosh staged some two dozen-plus numbers of Lehrer's best, bawdiest, grisliest and most malevolently delightful views of his fellow creatures.

It's good news, because the rest of the news is so bad these days that Lehrer neither performs nor writes any more. (He once said, and is quoted in the show, that "satire was made obsolete when Henry Kissinger got the Nobel Peace Prize.")

Boyish and fit, Lehrer (who is 53) spends half a year teaching at the Univerity of California, Santa Cruz and the rest of the year "hanging out" in Cambridge. It was while he taught mathematics at Harvard that he first started amusing friends with his rhyming disaffections. He wrote "Fight Fiercely Harvard" sometime in the late 1940s -- "sophomoric," he says now, "is putting it mildly."

... Come on, chaps, fight for Harvard's glorious name

Won't it be peachy if we win the game? (Oh goody.)

By his own characterization, Tom Lehrer has a very short attention span, an inability to make a commitment.

Because of it, he says:

* After 11 years of splitting his year between Santa Cruz and Cambridge he still has no place of his own in California. (But he can't stay there year 'round because, he says, "your brain turns to Jell-O there.")

* He won't go to movies that are longer than 90 minutes.

* He finished his PhD requirements but never wrote his thesis.

* He never married.

* He tried show biz as a performer twice. (And wrote a series of songs for "Sesame Street" and for the TV series "That Was the Week That Was.") And then left it.

He says, "I don't think I could have sat through 'Nicholas Nickleby,' let alone marriage. That's a commitment and I'm not into that.

"It's very consistent in my life, this lack of commitment. I can't decide where I want to live, who I want to live with, if anybody, what I'm going to do for a living. It's always let's see what happens... Next week I'll decide..."

Meanwhile, Lehrer is a closet tapdancer -- for fitness, he emphasizes, not show. He teaches a course at Santa Cruz about musicals because he said he believes they are essentially dead -- which, he says, makes them appropriate for teaching. (The last "great" was "Fiddler on the Roof," he says.) He loves old movies. (It was a Fred Astaire number that started him tapping away.) Despises most TV (except for a few things like the early "Saturday Night Live," "before it got too vulgar.") Oh yes, he says, he "watched about 10 minutes of 'Dallas' once, just to see what everybody was talking about. And that's it for contemporary primetime programming." Nor will he appear on TV, in part because of those old days when "they" wouldn't have him. He recalls, back in the '50s, "'The Ed Sullivan Show' people coming into the Blue Angel [where he performed in New York] and saying, 'Gee, we really love your act, and if you ever have any material we could use we'd love to have you on the program...'" And in part because "I've got to draw the line on invasion of privacy."

Dispite his showman's sense of timing and the witty and sardonic repartee that tied his songs together, Lehrer was never really a confortable performer. "The deadpan," he notes, "was a wonderful defense. One of the terrible things about being a performer is to say a joke and then have the audience not laugh. I couldn't face that ta-da ta-da ta-da joke. Pause. Silence. That's obviously awful. So I would just go on and on and if they wanted to interrupt me with langhter, I would stop. And if they didn't, I could act as if it wasn't supposed to be funny."

But Lehrer doesn't find the news funny anymore. "Oh sure, every once in a while there is something amusing, like Reagan removing the head of the civil rights commission because he was for civil rights. That's funny. But the rest of it is pretty scary. It doesn't inspire me to think of anything funny. It inspires me to get mad or scared or whatever the appropriate response, but not to rush to the piano and toss off so many funny things."

Then he adds, "One of the problems is that the problems are different now. It's so much more complicated than in our day when we all knew where we stood. It was very clear that Adlai Stevenson was a good man to a whole bunch of people like myself, and we knew there were people out there who voted for Eisehnower, because he won. But one didn't exactly meet any of them."

Lehrer hasn't stayed in Washington for the "Tomfoolery" opening. He back in Santa Cruz, where he teaches a course in the applications of mathematics to the social sciences as well as the one on musicals.

But he has spent most of the past six months with one "Tomfoolery" production or another. He was a little uneasy about the South African one, and ended up signing over any royalties to anti-apartheid causes.

He is quite naturally pleased that, even though the number of people who have seen him perform is relatively minuscule compared with those who have heard one of the million and a half records he's sold, he is still quite marketable. In addition to the recording of the British company of "Tomfoolery," there is a songbook ("Too Many Songs by Tom Lehrer.") Lehrer grins when he says, "We get to the T-shirts next... I don't know what the next step is in making this a vast conglomerate... but seriously, it's nice. Take something like the 'Irish Ballad' ["About a maid I'll sing a song... who did not have her family long... not only did she do them wrong, but she did every one of them in..."]. A funny idea in 1947 and I wrote it down to sing at a party. But in my wildest dreams, I wouldn't imagine that 33 years later people would be singing it in public on a stage...

"And that other people would be laughing."