1- When someone masturbates just after they've finished masturbating, there can be a short period of time between faps.
2- When someone is masturbating for an extremely large ammount of time with no effects (without "cumming") to the point where the arm is extremely tired and the dick feels numb.
3- When someone keeps on masturbating after they just came, generally stopping before a second cum.

In any case, Overfapping is hazardous and could possibly lead to problems with the penis.
1-
Bob: "Yo! Yesterday, I found this amazing video! It was so awesome... I kinda Overfapped..."
Jake: "Really? How many times?"
Bob: "....Seven..."

2-
Bob: "Yo! Yesterday I found this boring ass video... It was sexy though, so I spent the whole 2 hours masturbating, but nothing happened..."
Jake: "Ha, you were Overfapping dude, that's no good..."

3-
Bob: "Yo! Yesterday I was super-horny, so after watching a full length porno movie and cumming I just kept on beatin' my meat!"
Jake: "Seems like you Overfapped bro! ...Why do I even need to know that?"
by TheDeerInTheHeadlights May 8, 2013
Get the Overfapping mug.
what happens when men have too much time on their hands
man see you gtg get some sleep
alright dont overfap
by notgreg January 6, 2014
Get the overfap mug.
The act of fapping too hard for an extended period of time, resulting in your balls hurting for a while (usually the rest of the day/night)
Man I overfapped last night and I couldn't fall asleep for hours!

Fapping feels good as long as you don't overfap.
by stealthfapper69 September 5, 2016
Get the overfap mug.