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
Ok, from what I have gathered, Rishi Sunak also got fined for the partygate scandal and that was the reason Boris Johnson resigned as Prime Minister as he was also complicit in the partygate scandal. This is why the UK is a laughing stock. We can't keep phoning up other members of parliament to become Prime Minister without being elected because that goes against democracy. Mind you, the BritishGovernment have only ever cared about democracy when it suits them.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).