This is my second instructable, so don't be too harsh...
The name is self explanatory, a piece of plastic that blows up when you throw it, but it has a special feature. It has a pin that actually prevents it from blowing up from things like accidental drops or anything of that nature. Once the pin is out, it is very sensitive and will blow up if dropped from about 2 feet above the ground. (The pin will not save it from throws though. If you THROW it with the pin in, it will blow up.)
I give credit to Darth Tso and Fred Da Bunny for the idea of the pin and the design. Thanks guys!
Step 1: Building the Grenade
Easy as pi. (3.1415926535...) lol. That must REALLY hard, JK it's really easy =P
Step 2: The Pin.
This has to be the hardest step ever.
Step 3: Rubber Bands.
These are crucial to the grenade not going off by accidental drops. (Make sure you have the PIN in the grenade at all times during this step, otherwise it will either IMPLODE or BLOW UP in you FACE!!!) (The pin keeps it stable for those of you who were wondering why you had to keep the pin in.)
Once the rubber bands are on, you can take the pin out to throw it, but if you aren't throwing it, keep the pin in so it won't blow up accidentally.
Step 4: Grenade Strap. (Optional)
I came up with this when I was toying around with some chain links.