HerpDerpp is used generally when someone is being stupid, or they've epically failed at something. It's usually said after someone makes a particularly stupid statement, or they make a funny mistake.
Example: Ms. Marinho asked Lynnzy to read out loud, and Lynnzy stuttered. When she had recovered and finished reading the paragraph, Tobias, Jacob, Damian, Keith, and Steve all yelled 'HERPDERPP' right in her face.
by badass techies October 07, 2014
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