'Gregging' is the process by which an individualmasturbates into a hat. Though this is its definition, it can also be used to describe an individual resting his penis in a hat, and/ or using the hat to masturbate. To 'Greg' someone is to steal their headwear, and perform one of these heinous acts using it.
Example 1)
It has commonly been used to make amusing adjustments to songs:
"Gregging,Gregging you... filling up your beret with my penis"
Example 2)
Ray: "Man, what the fuck is up with your hat?"
James: "you wont believe it, Some punk gregged it last night at the party!"
Ray: "Ouch, dont worry about it, weve all been there before"
Example 3)
Mark: "Hey, look at that blokes hat, you want to greg it?"
Bryn: "Hell yeah!, ill go first"
30 minutes later
Man with Hat: "Bollocks"
A famous Italian comic and showman, actually a reptilian and intergalactic tax fraud hiding on earth from the space IRS. He's in charge of the new world order with other sionist Martians such as Mike Bongiorno and the mythological creature known as Gabibbo, together they rule the earth and sponsor terrorism around the globe