A verb to describe the action of somebody or something that is acting in a manor that would cause somebody to think that they are mentally handicapped.
When Iryna fell on the floor and started laughing uncontrollably for absolutely no reason, Ryan and Matt mutually agreed that she was derping out.
by NotBigSurprise March 29, 2011

Free Daily Email

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

Emails are sent from daily@urbandictionary.com. We'll never spam you.

×