Sweet Teeth is a candy monster from the episode "Beast Halloween Ever". Amanda and Beverly disguised themselves as Sweet Teeth in order to steal everyone's candy so Amanda would beat Mikey in getting the most candy.
In the end, the real Sweet Teeth came to the human world and scared Amanda, until she asks if he knows a handsome beast named "Phlegm Hocker". When Sweet Teeth says "candy", (which is apparently all he can say) she thinks Phlegm's taken and asks him out instead, terrifying him in return.
Sweet Teeth is a light blue monster with a pink-and-white-striped elephant-like trunk with small teeth, green ear tufts, and buck teeth similar to Timmy Turner's.