fonch Share definition Flag (aka The Fonch; orign American) n. 1. the mangina; n. 2. where a male takes his penis and sticks in between his legs to create a simulated vagina; v. 3. used in expression (see below). 1. You didn't just show dad 'the fonch' did you? 2. Fonch-tastic! fonch by Doc Nutz March 18, 2003 0 0 Get merch Get the fonch mug. Buy Now — $32.95 See more merch