First, you need to get a push-button switch. Take the wires of it and connect one to a nine volt battery connector and the other to a solar igniter (used for launching model rockets). A very thin piece of stereo wire will usually do the trick if you are desperate, but I recommend the igniter. Connect the other wire of the nine-volt battery to one end of the switch. Connect a wire from the switch to the other lead on the solar
Now connect the explosive (pipe bomb, m-80, COý bomb, etc.) to the igniter by attaching the fuse to the igniter (seal it with scotch tape). Now dig a hole; not too deep but enough to cover all of the materials. Think about what direction your enemy will be coming from and plant the switch, but leave the button visible (not TOO visible!). Plant the explosive about 3-5 feet away from the switch because there will be a delay in the explosion that depends on how short your wick is, and, if a homemade wick is being used, its burning speed. But if you get it right... and your enemy is close enough......... BBBBBBBOOOOOOOOOOOOOOOOOOOOOOOOMMMM!