You have options actually.

You can run, if you are willing to give up the comfort of your warm bed.
You can toss it through a window (and I mean through), if you are willing to live with the cold air streaming in.
You can do nothing, if you are willing to find out if it will go off or not.

I know nothing about the condition of that grenade under your bed, but if the pin was still in it, I would lay down and go to sleep and worry about it later.

Military service was still mandatory in the 80's. My forbidden knowledge of explosives and such provided by the very entity that forbids it.