It simply involves rubbing ones "ball sack" until ejaculation. By acheiving orgasm through merely rubbing ones balls, you can be described as "sacking off" as opposed to the more usual "jacking off".
Clearly can be used in many tenses, and as a verb, noun and adjective;
I, he, she is going to sack off tonight.
I, he, she sacked off last night.
I, he, she had a really good sack off last night.
I, he, she is a total sacker offer.
"Stop talking shit, you sacker off"
"You're a real sack off"
"Last night was amazing, my girlfriend came round for the annual blowjob and steak day (March 20th - google it!!), but she surprised me at dinner by sticking her hands down my pants and giving me the most amazing sacking off"
dude 2: well i think it was ok because she wanted my cock
dude 1: fuck you its a sack off now bitch
dude 2: ill fuck you up like i fucked your girl
Gazzy P is in a right mood I'm gonna sack him off soon
I might have to sack-off you. I will give you 10mins then we're bailing to the next club.
similar in use to the Aussie 'Rack Off'
The word 'sack' replaces 'fuck' in other uses:
Sack All - nothing
Sackin' Ada - 'kin'ell.. an exclamation of surprise
Sack it off - to get rid of or finish (also Sack it)
Sacked Off - fed up with or bored with or pissed off with
kid 1 "who's brock me pencil, was it you?"
Kid 2 "Sack Off, I ant ad it"
Kid 1 'Gizza Chip mate?'
Kid 2 'An you can Sack off an all Get yer own chips'
Alternative 'clean' Lyrics to 'Its so Easy' by Guns 'n' Roses
"I see you standin' there, you think you're so cool
Why don't you just...