How do you like your comedy? Broad? Slapsticky? With a side of macho repartee? Then maybe you’re already busting a gut over the trailer for My Fellow Americans (opening Dec. 20), which shows Jack Lemmon and James Garner as rival ex-Presidents who band together — and bicker — when framed by current Commander-in-Chief Dan Aykroyd, a pork-bellied jogger with a Southern-fried accent (hmm). Is this a lowbrow pitch for a higher-brow caper, or should we expect a lot of locker-room gibes from two grumpy old diehards out for vengeance? ”The shortest distance between no laugh and a laugh is a kick in the groin,” says director Peter Segal, who admits the ad plays up the physical but calls the movie ”slightly smarter” than his last, Chris Farley’s Tommy Boy. You’ve been warned.