mugface Share definition Flag 1. An adjective to describe a person with mug-like features, or who has just done something which is clearly stupid. "Oi, you, stop impersonating an ambulance. This is a Church. You Mugface." mugface by Dave Kaboshi July 12, 2007 0 0 Get merch Get the mugface mug. Buy Now — $32.95 See more merch