BlueFlame

one of my friends has an impressive speciman that consists of:

1 x PVC Tubing
1 x PVC cap with fasioned latch
lots of x (I think) deoderant or lighter fluid
1 x old Piezo electric lighter disposible thing (not too sure what it is actually called)
10 x old stolen tennis (he lives next to a tennis club!)

You can picture the assembled gun. maybe i should ask him for another demonstration. What it lacks in accuracy it makes up in noise, and the cool-factor is extremely high!