Top Definition
To covertly masturbate in the presence of others without their knowledge.
"At the bar I tried to listen intently to my friends at the table, but I was ninja masturbating and needed to finish off quickly."
by ZombiUnikorn January 25, 2009
Free Daily Email

Type your email address below to get our free Urban Word of the Day every morning!

Emails are sent from We'll never spam you.