TWACK v. To strike with great force using the back of the middle finger (usually the nail) after coiling it under pressure against the opposing thumb. Accomplished twackers can inflict great welts upon their victim's flesh.
That turd cutter pissed me off, so I twacked him right in the munt!
On the first twack
Pope jumped like a macaque;
On the second twack
Pope was taken aback;
On the third twack
Lost his marbles the old hack.
(A. S. Pushkin)
The term 'TWOC' is an acronym for 'Taken Without Owners Consent’ (Taken can be replaced also with 'take') apparently originally used on police documentation, the term has become a popular part of conversation amongst the younger community. The word can be used as simply 'TWOC' or 'TWOC'ed', depending on the situation. The people most likely to be found using this word are young anti-social vandals.
"See that van there?...i'm gonna TWOC it"
"y'know what bill, fuck off. I TWOC'ed your car yeah, but jesus, i haven't heard the FUCKING last of it!"