Term used to desribe eating one large meal in a day. It's breakfast, lunch and dinner combined into one power meal.
"Hey Travis. You hungry?"
"No, dude, I already had dunchfast and now I've got to go throw up out of my butt!"
"Gross, thanks for the info. I'm going to have my girlfriend give me a blumpkin."
A meal that is eaten as one's breakfast, lunch, and dinner.
Man, I woke up so late yesterday I just had dunchfast.