In Knocked Up, the sex scene has "Rock Lobster" playing. And, quite frankly, that's the sort of bizarre, just-freaking-going-for-it-no-matter-how-weird humor that made me love the end of The 40-Year-Old Virgin with "Age of Aquarius," and when Andy yelled "OHHHH KELLY CLARKSON!!!!" If the rest of that movie had been so crazy, I might have liked it instead of despising it.
Judd Apatow is far from brilliant, but at least Knocked Up is funny and sweet as opposed to... terrible.