President Obama at his Jan. 14 news conference. (Carolyn Kaster/AP)

President Obama apparently forgot a cardinal rule at Monday’s news conference: It’s always the last one that gets you in trouble.

For example, it’s always the last ski run, the one before sunset, where you end up blowing out your knee.

Or it’s that last drink, the “one for the road,” that gets your fender bent — or maybe much worse.

It’s the last bet at the poker table, when you’re on a streak, flush with chips, and you say “all in.”

Then there’s that last e-mail in a testy exchange, the one where you’ve finally lost it and rip into the person — then hit the “reply to all” key.

And so Obama on Monday, after blistering Republicans over the debt ceiling, responded to a question by New York Times reporter Jackie Calmes about whether part of his problem with Republicans was that “you don’t socialize enough.”

This led to a somewhat rambling answer in which Obama says things like: “I’m a pretty friendly guy;” “I like a good party.” And the girls are older and don’t want to hang with him so much these days, “so I’ll be probably calling around, looking for somebody to play cards with me or something, because I’m getting kind of lonely in this big house.”

That naturally fired up the twitterverse big time, resulting in things like: #ObamaNeedsFriends.

And remember the last question at a July 22, 2009, news conference, also in the East Room, when Chicago Sun-Times reporter Lynn Sweet asked him about the arrest at his home of Harvard professor Henry Louis Gates Jr.

What might that “say to you. And what does it say about race relations in America?” she asked.

Obama started off perfectly, saying Gates was a pal, “so I may be a little biased.” He followed with: “I don’t know all the facts.”

Excellent end. Oh, but then he meandered into the “Cambridge police acted stupidly.” Which soon got us to the famous “Beer Summit” with the arresting officer, Gates, Obama and Vice President Biden sitting around a table near the Rose Garden.

So don’t take that last question — especially when it’s from sharp, veteran reporters.