If you've never seen an episode of CBS' How I Met Your Mother before—or if you watched a few back at the beginning of season one and then gave up on the show—you've got a prime opportunity to see it at its best tonight at 8 p.m. (7 central). The episode "Slap Bet," widely regarded as one of the funniest half-hours of 2006, will be re-airing. If you don't like it, chances are that HIMYM will never be your kind of sitcom. If you do like it, be warned that the show has never been quite this great before or since. (Though it comes close sometimes.) And if you're already a fan, watch it again—especially if you're part of Nielsen family. According to all reports, HIMYM is "on the bubble," and may not be renewed for next year.