Grenade Theory
THE GRENADE THEORY:
1. Throwing an object at someone else for no reason is 'dread'.
2. 'Grenading' someone for no reason is perfectly acceptable.
3. Once 'Grenaded', the victim cannot retaliate unless to 'Grenade' them back.

Got that?

HOW TO GRENADE SOMEONE:
1. Choose your object. It can be anything EXCEPT a grenade. Obviously.
2. Throw your object at your victim, whilst shouting "Grenade!"
3. Duck.

Please note that step 3 is important. Many people do not duck after 'Grenading' someone, making the 'Grenading' void, and meaning the victim can retaliate.
Bob: GRENADE!
*throws brick at Gary and ducks*
Gary: What the fuck! You bastard!
Bob: Haven't you heard of the grenade theory, man?
Gary: Oh, right. Carry on.

OR

Bob: GRENADE!
*throws brick at Gary*
Gary: What the fuck was that for?
Bob: Haven't you heard of the grenade theory, man?
Gary: YOU DIDN'T FUCKING DUCK!
*Gary beats Bob into a pulp*