Hand Grenade
Hand Grenade is Snake's Standard Special Move. Pressing and holding the special move button once will cause Snake to pull out the pin, depressing it will cause him to throw it. The distance that the grenade is thrown can be controlled by pressing forward, backward, or pressing no direction at all. Except when you drop the grenade by shielding you can pick it up as you would with an item and throw it extremely far due to it's light weight. A maximum of two grenades per Snake can be thrown, no more can be produced until one of them explodes.
If Snake is close to a grenade when it goes off, he will cover his ears.
Unlike Link's bomb, it does not explode on contact and the enemy can grab it before it explodes. The grenade can be "cooked" by holding B (as it is thrown when B is released) to reduce the time between the moment it's thrown and the moment it detonates--the grenades usually last for about three and a half seconds or four seconds, so "cooking" it for three seconds and then throwing it when it's close to exploding is a wise strategy.
Also, Grenades are unique from Bombs or Vegetables in that they take priority over held items; that is, Snake will still perform the move while holding an item. Anything he carries will be dropped as soon as he presses the Special button.
Wario is able to eat the item without taking damage. It makes the explosive effect, but takes no damage. The actual explosion happens later, which can be dodged if Wario simply moves away from it.
Origin
Hand grenades have always been a staple offensive tool the Metal Gear series. They can easily be found in lockers, store rooms, or obtained from enemy soldiers.
