A "Jack Cunt" is someone who is selfish, unwilling to work and use energy during a task involving more than one person. The person who has been deemed a "Jack Cunt" may also try to use excuses to avoid performing the required task, which usually involves them suddenly disappearing, then reappearing after the task has been completed. Jack Cunts will always think about themselves first..

Got the covid-19 vaccine

Someone who by doing 'jack shit' in a team environment becomes a cunt because the other people in the team have to pull the weight of that person and do extra work.

The biggest cunt alive, ever

A Jack Cunt is someone who offers fuck all help, is a righteos cunt and usually drinks 5 times more than the money in their wallet or fucks off come bill time, also refered to as doing an Adsy.

The act of being a cunt, and doing everything possible to Jack people off.