A pissed off potter is when you get a wand and wipe it on your ass to get shit on it. Then you go up to someone you dont like and put the harry potter scar on their forehead. After realizing what has happen, they become pissed off making them a pissed off potter.
Michael pissed me off today, so I got him back by making him a pissed off potter.
A pissed off potter is when you giving it to someone up the ass. After getting a rusty trombone, you pull it out and put a lightning bolt made out of shit on her forehead. After realizing what you just did, she becomes pissed off.
After getting it up the ass, Michael received a pissed off potter to top it off.