The act of embarking on an endeavour so titanically stupid and damaging, that your peer-group will hate you forever.
For extra effect, a "full sunak" should begin with announcing your intent in the most embarassing situation possible (eg on national TV, while standing in the torrential rain without an umbrella)
We were on this road trip with Carl, and his car caught fire. Turns out that when he was joking about having poured petrol everywhere, he wasn't joking. The whole thing was a proper full-sunak
A wet fart that can occur during or after anal sex.
The guy I picked up at the club was going to stay all night, until I sunaked on his face. He left pretty sharpish after that.
A rich self entitled unelected twat for the United Kingdom
Rishi Sunak is a very rich prime minister!