Trouty Mouth is an original song featured in Original Song, the sixteenth episode of Season Two. It is sung by Santana. She is accompanied by Tina on the piano. Before being able to finish the song, Sam interrupts, angry and offended with the constant mouth jokes. She wrote this song with help from Tina.
After the New Directions discover that they are forbidden to sing My Chemical Romance's Sing, Rachel suggests that they should write original songs for Regionals as it will increase their chances of winning. Santana protests when Rachel and Quinn offer, saying that all of them should have the chance to write their own songs. Thus, Will assigns them to write original songs.
After Will rejects Hell To The No as a song for Regionals, Santana again offers "Trouty Mouth," saying she has written another verse for the song (though Sam objects by holding up a "Hell No" sign). The additional verse was not performed, or included, in the version released on iTunes.
Is that how people's lips look where you come from in the South?
I love suckin' on those salamander lips.
Wanna put a fish hook in those lips, so cherry red
If you tried hard enough, you could suck a baby's head!
Oh, yeah-eah, yeah.
On Tuesday, March 15, 2011, the air date for Original Song, Trouty Mouth was a trending topic on Twitter.
Though originally unintended, Trouty Mouth was released on iTunes due to popular demand, along with Big Ass Heart.
Santana said she wrote another verse for the song, but does not perform it since both Sam and Will object.
In Born This Way, Sam admits that he is, or used to be insecure about his mouth through his T-shirt in the group performance.
Naya Rivera said in an interview that it turned really sexy. More sexy than she intended it to be.
The song was written by show composer James S. Levine and co-creator Ian Brennan. 
In the song Tina plays the piano (Jenna Ushkowitz learned to play piano for Spring Awakening).
This song is referenced in Naked, the twelth episode of the fourth season. In Blaine's documentary for Sam, Santana's testimonial was about Sam helping her become a songwriter. She then sang some verses of the song.