In the episode The Way We Weren't, after kissing with Marge at the age of 10, Homer has several fantasies. One of which includes drinking Kool-Aid out of the Kool-Aid Man.
In the episode The Simpsons Guy, during the court case for Duff Beer and Pawtucket Patriot Ale, The Griffin Family all said "Oh-No!", which cued the Kool-Aid Guy to break through the wall of the courtroom. However, he failed to do so. Peter then received a phone call from him, saying that he was in the wrong Springfield, while standing in a random, unrelated courtroom, leaving a hole in the wall behind.