Jerk Off: - (used as a verb) slang
To masturbate, usually used to refer to men.

Jill Off: (verb - slang)
Used to describe a woman to masturbating.

Jock Itch:
Jock itch is caused by a fungus that lives on your skin. The name of the fungus is Tinea cruris, and is related to the athlete's foot fungus. A common fungal skin infection in the genital area of men that is caused by wearing tight clothing, sweating, or not drying the genitals carefully enough after bathing.

"Just Good Friends":
A phrase that defines a relationship as non-sexual. As in: We’re just good friends.