Charles Marvin Green Jr., better known as Angry Grandpa or simply AGP, was an American Internet personality. His videos were featured on HLN's Dr. Drew, TruTV's Most Shocking, Rude Tube, and MTV's Pranked. wikipedia.org
Definition #2 for "angry grandpa"
Angry Grandpa was the nickname given to Charles Green, an elderly man known for appearing on The Angry Grandpa Show, a YouTube series co-hosted by Green?s son Michael ?Pickleboy? Green and Bridgette ?Princess? West.