During the show within the movie, several popular songs are performed in unusual ways. Cee-Lo Green's popular song (under its more family-friendly name 'Forget You') is clucked by chickens, with no intelligible lyrics.
Not to mention a clever Stealth Pun; there's no way it's a coincidence the offending lyric is here replaced with a literal cluck.
Similarly, although 'Smells Like Teen Spirit' is performed, all the potentially objectionable lines are given to Beaker - such as 'My libido' or 'A mulatto'. Both are excellent examples of the Muppets' special gift for making Bowdlerisedd lyrics funnier, not just more family-friendly.
When Piggy and crew go to acquire a celebrity host so the show can go on, they go to the studio. When they reach a certain trailer, Jack Black comes out in a motion capture suit and yells, "Hey, I told you, I'm not finished putting on my balls!". It honestly wouldn't have been so bad if he hadn't said that last word with so much force...
He also becomes the first human to go face-first into Piggy's crotch...admittedly, she WAS attempting a kung-fu move on him at the time.
During Life's a Happy Song, a hippie/stonernote Willie Nelson sings, "Life is full of highs."
When confronting Miss Poogy, a rather husky-voiced and angry-looking Moopet, Miss Piggy takes a not-so-subtle look at Poogy's crotch area.
Miss Piggy: Listen ..." [crotch check] "sister ..."
The showgirls in Mr. Richman's office.
When Walter tells Kermit, "You give people the greatest gift that can be given," his response is, "Children?"
During the scene with Pepe's cameo, the song that is playing is "Time of My Life" from Dirty Dancing. This wouldn't be so bad, if they hadn't decided to have Piggy to be singing the most suggestive line in the entire song at that point. (Baby, I know what's on your mind when you say/'Stay with me tonight').