When a person, male or female, tends to stroke your penis until you get off. Otherwise known as a handjob. It is another way to have someone else masturbate you when you really do not want to have sex.
Last night Sarah asked me, "Can I jack you off? So, I said "sure".
"Wow, I really would love to jack you off, baby!"
To provide an action or service (good or bad) in the servers best of ability. It can refer to a sexual action from male/female or harmful act using excessive force.