A combination of dinner and lunch. Also the sound when you try to surprise someone with anal sex with a raging hard-on (or strap on) but the recipient is wearing a substantialbutt plug that prevents said butt sex.
Random Guy talking to his friends: Oh I had Dunch for lunch.
Random Guy Talking to his friend random guy 1: Woah you had Dunch for Lunch I thought it was Linner but okay.