Step 1: The Base
Build this base, it is 5 by 5. Make sure to build it out of sand.
Step 2: Second Base
Put another layer as shown, the torch in the center does not need to be there(in fact, it works better without the torch :) )
Step 3: The Bait
Put a valuable block on the torch (or one above the second base, if you chose not to use the torch) then put a torch on the bait.
Step 4: Sand
Put sand on top of the torch.
Step 5: Keep Stacking
Keep putting sand on torches until you get a 3 by 3 area, then build a pyramid like you did for the base, place a torch on top.
Step 6: Finish
Now you are finished! Have fun trolling your friends!