Nathan Lane and four chorus-line guys performed a funny spoof, about Brokeback Mountain a la “Oklahoma” on Late Night with David Letterman last week. Funny like skits on the “Carol Burnett Show” used to be in the ’70s. Funny if you just sit back and give in to the lame-itude for the sake of seeming like a good sport. But if you think about where Lane is coming from for more than two or three seconds…no, don’t! Then it won’t be funny. And nobody wants to be a sourpuss and not laugh at a venerated funny guy and Tin Pan Alley legend who happens to be a bit of an asshole. But if you take the skit as Lane’s audition for the Oscar-telecast gig, then I guess it was fairly successful.