Gurglemax is a laxative that Stewie and Brian do a commercial for in "Cat Fight".
When Stewie and Brian succeed in getting Quagmire's cat cafe shut down, the latter thanks Stewie for being with him. He notes that he was happy to help as they hadn't done anything together since doing a fiber commercial in which they had to find code words for pooping. In the cutaway gag, a cup of coffee triggers Stewie's bowels and he loses control before making it to the bathroom.