A letter from the alphabet, don't you fuckin' know?
A, B, C, D, E, F, G, H, I, J and it goes on.
to punch another individual with great force
"Don't mess with me or I'll j you in the face!"
The person that gets "J" to the first letter of their first name will grow over a 10 inch cock in their 20s.
"Jez have grown his cock from 3 inch cock to a 14 inch in his 20s"