If it's Tuesday, this must be "Just Our Luck," a new ABC sitcom that proves a situation can become belabored in only a matter of minutes if true, resolute laboriousness is deployed. In the program, at 8 on The New Season Channel 7, T.K. Carter plays Shabu, a black genie who pops out of a lamp that has found its way into the clammy hands of a Santa Monica weatherman.

Shabu can turn himself into a soul trio at will or summon up scantily clad damsels ripe for the, er, summoning. Whatever he does, Shabu seems hardly the sort of character in which image-conscious blacks could take any pride. George Jefferson has his redeeming qualities; Shabu is just Steppin Fetchit in a bottle.

Actually, none of the characters in this television show is one in which any image-conscious human beings could take pride, either.

"Keith my man, wha's hap'nin'?", Shabu says to his reluctant new "master," played by Richard Gilliland like a poor man's--an absolutely destitute man's--John Ritter (and isn't John about as poor as it should get?). The comic conflict arises from Shabu's jivey hedonism clashing with the weatherman's squeamish conservatism. When his employers at KPOX-TV tell him to put more pizazz into the weather forecast, he says, "Maybe I should just paint the temperature on my butt and moon the audience."

And does that ever tickle the laugh track's fancy!

Carter probably retains as much dignity as one could under the circumstances, but from the way the show plays, you get the feeling that all concerned, including director John Astin and writers Bob Comfort and Rick Kellard, must have said to themselves at one point, "To hell with dignity, let's wrap this sucker up."

Tab Hunter makes a brief guest appearance that approaches being humorous, and there is one cute joke involving the genie's eagerness to douse the weatherman in luxury. He presents him with an automated teller right there in his own apartment. You don't have to put in a card or press buttons; you just pound it with your fist and growl, "Hey--gimme some money!"