1. Verb - Aimlessly wandering when you could have been doing something useful.
1. Derp: Hey man, what were u doing in the market?
Herp: Nothing man. I was just derping around.
2. Mom: Stop derping around on Facebook and study.
Son: Shut up, woman.
Mom: WHAT DID U SAY??? Herp derp.. blah blah.. blah blah.... No XBox for a week.