You must (a)pply it to pull its pin and a 5 second timer will start. Once the timer counts down to one it will explode catastrophically, no matter whether it is in your inventory or not. <br>
Throw it or drop it and run.
== Trivia ==
[http://en.wikipedia.org/wiki/Holy_Hand_Grenade_of_Antioch#Holy_Hand_Grenade_of_Antioch The Holy Handgrenade of Antioch] is used to defeat the killer rabbit in [http://en.wikipedia.org/wiki/Monty_Python_and_the_Holy_Grail ''Monty Python and the Holy Grail.'']