i use to use wd 40. i use to light the red and white straw and spay away, but that is really stupid to do because you can see it coming back to bottle and u. i use to also write stuff on the ground and try to write stuff so that you can read it. you need alot of wd 40 to keep it going, but it only worked for like a good 10 to 15 seconds. and when i was in 11th grade one of my friends blew up a propain tank in a grocery kart. it looks really coo and sounded coo, but i will never do that again because it was scary as hell. it had a delay before it went boom.