/Gonna shoot you right down ...
Behold the tiny flare pistol, from Berloque.
As you can see from the picture, it is small enough to fit on your keychain.
Itty-bitty as it is, using pin-fire blanks that need nimble fingers or tweezers to load, the single-shot pistol will launch a mini-flare in assorted colors -- red, white, green, yellow, like that. They claim a height of twenty-five meters, and that looked to be about right.
I bought one for my son for his birthday, and we gave it a go last night.
Comes with twenty blanks and ten flares, and while you can buy spares of both, they are pretty spendy -- couple refills of twenty-five rounds each will cost you as much as the gun.
Because the barrel of this gadget has to be drilled through so that the blank can ignite the flare as it launches, this means you can't point it at somebody because the blast will blow out through the muzzle. (It also means that if you happened to be holding a #7-1/2 BB from a shotgun shell and accidentally dropped it and it somehow fell into the muzzle and you accidentally jammed it in deeper with the little ramrod used to eject the spent blanks while trying to remove the BB, you would have a teenie-weenie smoothbore single-shot pistol.)
Not that I would ever tell you to do this. That would be dangerous, for if you then fired the pistol thus accidentally loaded in order to remove the BB, you might find that the blank charge would be sufficiently powerful enough to propel the pellet at a velocity that would punch a hole right through a cardboard box. A true mousegun.
Good luck with a barrel as long as your little fingernail trying to hit something with it, though.
An amusing toy, though, for those of you who find such things interesting.