Unlimited Monkey Bombs Glitch

Monkey bombs are the best way to buy more time when you are about to die or revive a fallen player without having zombies all over you.  The only problem is that you only have three of them but I found a cheat that allows you to trade a monkey bomb for a grenade.  To do this cheat you need to first throw all of you monkey bombs.  Then you throw a grenade at the ground.  Lastly you go by and press L2 and you will get another monkey bomb but you will have to run away from the grenade because it will still blow up.