look up any word, like half chub:
 
8.
Jack Off: When a male masturbates.
Fank is going to jack off in his room.
by ~Keyona January 09, 2004
 
9.
if you're under 13: you're not cool enough to know what it means. come back when you wake up and its sticky in your danger zone.

if you're over 13: why the FUCK would you need to look up the definition of "jack off?" did your balls not drop yet?
why the hell would any guy who's hit puberty need to look up what "jack off" means?
by un-dumbassify yourself, please January 03, 2010
 
10.
To masturbate until the point of ejaculation is reached.
Oh, oh, ho, oh my god, wait.. wait a..., oh OH SHAZAAAM!
by gabe April 21, 2005
 
11.
When A Guy Holds His Dick And Rubs His Hand Up And Down Getting Faster Until It Feels Good And He Sperms.
My Friend Doesn't Get Any Pussy So He Likes To Jack-Off.
by *JeNnA* May 04, 2004
 
12.
To masturbate; the stimulation of a male's penis until orgasm is achieved and ejaculation occurs.
Jill didn't want to have sex right now, so Jack decided to jack off.
by Phillip Knowles January 18, 2006
 
13.
n. A male who "jacks off"; v. to masturbate. adj. Dumbass
n. He's such a jackoff.
v. Don't let me catch you jacking off again.
Adj. That fucking jackoff guy.
by Ben fuckermother August 26, 2003
 
14.
To stoke the penis up and down in a motion like if you were to shake milk.
Today when I shook my chocolate milk, after 20 minutes it turned white thanks to the jack off motion.
by Anonymous October 28, 2003