Top Definition
Related to methamphetamine, crank, gilly. If you've ever met a hardcore tweaker they'll report seeing monsters and other hallucinations after being up on the drug for days. Some call them the gillymonster.
fuck dude this one time i was up for 5 days straight and the fucking gillymonster was going to fucking get me!
by RC November 03, 2004
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.