Unwanted pregnancy might sound like a risky subject for slapstick comedy, but Knocked Up is from writer-director Judd Apatow--so we are in the hands of a man who likes to push things. And like Apatow's predecessor, The 40-Year-Old Virgin, Knocked Up is a shaggy crowd-pleaser, a comedy strewn with vulgarity but with a sweet heart at its center. A one-night stand between the utterly mismatched Ben (Seth Rogen, his first starring role) and Alison (Katherine Heigl) results in said pregnancy, and the two people reunite for mutual support--even though they barely know each other. Ben's a slob who lives with four other guys, all of whom share the same stunted approach to maturity; Alison is a new on-air personality at the E! channel. That these two eventually develop a shared understanding and affection is perhaps the movie's biggest stretch (some of the male-humor jokes amongst the guys are idiotic enough to test anybody's hope of civilizing them).

Rogen and Heigl don't really jump off the screen, but, to be fair, the movie frequently needs them to play straight while the supporting cast cuts up. Virgin vets Leslie Mann and Paul Rudd are around to supply some humor, as Alison's sister and brother-in-law, and the four idiots who live with Ben (Jay Baruchel, Jonah Hill, Jason Siegel, and Martin Starr) are in their own zone of sophomoric bad taste. Still, by 40-Year-Old Virgin standards, this movie doesn't explode, and it sometimes feels ramshackle to the point of not being thought out. Apatow's indulgence of actors creates some fine moments (Paul Rudd seems to have most of them), but it can also make a movie feel flabby, and this one is overlong by the length of a belly. --Robert Horton