Not sure if everyone knew this already or if nobody plays MOHH anymore, but here's a trick I developed playing MoHH for 1 month. Okay go near an enemy. Cock the grenade into live mode but dont throw it. Now run towards him as fast as you can. The grenade explodes and both of you die.

What's the point you may ask?

When you're low on health or ammo, it's a good way to cancel out a death and a kill. Bad for your enemy though. If your enemy kills you though and the grenade hasn't gone off, there's still a chance he might walk over you and it will explode.