There are objects called fart cans which are actually what the name implies (they are also sometimes called fart spray): an ordinary aerosol spray can filled with something that purports to smell like flatulence--designed primarily for pre-pubescents and the criminally insane, one would presume.
I saw one of these when I went to a local food festival sort of thing with a friend when we were 11. One of the booths sold these and my friend bought one. His experimentation yielded the following results:
They don't smell that much like farts unless you really use your imagination.
They do, however, smell pretty nasty on their own.
If you spray them underneath a table, say, they're strong enough that the other people WILL notice.
The contents are flammable.
Ants on fire are funny.
I think it goes without saying that there's no actual use for these unless you're really immature, since the novelty wore off really, really fast even for us 11-year-olds, and we had to branch out into other means like setting ants on fire.
Now those things where you squeezed the envelope and it swelled and exploded, THOSE were cool.