Amid the crude jokes and iffy thoughts on weddings (they're only for women, per the movie, and men are only in it to "score") is the notion that men should form strong relationships so they don't have to pay someone to be their best man -- and that marriage should be based on love and trust, not how nice the person is or how much money they have in the bank.
Physical comedy and slapstick violence, including a grandmother catching on fire and falling over, a rough and aggressive groomsmen vs. grandpas football game, a man whose genitals are caught in a dog's mouth, and a lot of pratfalls.
Brief shots of topless women during the bachelor party, which also contains a dog licking peanut butter off a man's penis. Many crass references to the sex that's in store after a wedding (i.e., "I want seven vaginas up on my face").
Very strong language in nearly every line of dialogue. Dozens of uses of "f--k," "motherf---er," "p---y," "a--hole," "bitch," "d--k," "s--t," "douche," "cabron," and religious exclamations.
Many adults drink to excess (particularly at the bachelor party) and/or smoke weed (there's even a song about smoking weed).