Muffin man’d refers to the quotation of the interrogation scene from the movie Shrek in an online chat, as a call and response from users in chat, each user quoting one line after the other.
Do you know, the muffin man?
The muffin man?
The muffin man!
Oh man Mattymorgs twitch chat (HeroZone) was crazy last night. We must have muffin man’d like 3 times!!!