Big-Lipped Alligator Moment: The end sequence, a performance of the Hair number "Age of Aquarius/Let the Sunshine In" featuring the entire cast. This happens immediately after Andy and Trish's consummation of their marriage.
Hollywood Homely: Cal. Granted few people would consider Seth Rogen their dream man but he is average-looking at worst and certainly not "ugly as fuck" by traditional standards.
One-Scene Wonder: Jonah Hill as the guy who wants to buy the goldfish platform boots so he can wear them. He reappears again during the ending sequence above.
"Seinfeld" Is Unfunny: While plenty of comedy movies and shows had had lots of improv before, this was the first mainstream comedy in which all of the dialogue was ad-libbed or retroscripted for deliberately awkward comedic effect and was seen as a unique new way to do feature-film comedy in 2005. Now, it's impossible to find any live action comedy whatsoever that isn't created this way and by the middle of The New '10s, it's become seen as infuriatingly lazy.
Some Anvils Need to Be Dropped: There's nothing really wrong with being a virgin. Sex doesn't have to be integral to a healthy and meaningful relationship at any given point, nor be an indicator of a person's maturity.