Simple flatulence sound generator circuit?

I'm looking for a small (easy to conceal), battery operated, disposiable (not likely to be recovered after implemented) circuit, to imitate a person with a nasty gas problem.

It doesn't need to be particularly realistic, but a little better than a simple single tone buzzer. I'd like to use basic, descrete components (stuff on hand), and inexpensive.

At work, they've been upgrading/remodeling (ripped up the floors and walls) for about a month now, tell us about 2 weeks (likely another month). Porta-potties, in the middle of summer, in Florida... that's just too cruel. Thought a little prank for the grand opening was in order. Anyway, need to cut through some research and experimenting to get the sound. Figure I'll just put it on a simple 555 timer. Have to see the new improved faucilities to decide how best to conceal the device.

I figure somebody out there, at sometime has used a similar prank, so please share,

I think one of those toys that records sound and plays it back would be the simplist solution. Use the hand under the armpit noise to record.

There was a funny-as-hell story of some guys who make a pair of fake legs to make a toilet look occupied and they added a continuous loop mp3 player of grunts, "plops", etc but not ridiculously over-the-top. They went to a lot of work to make sure the acoustics of the recording would play back in a completely realistic fashion. They fooled everybody at work with the cyber-crapper. The janitor was afraid to confront the man in order to clean the bathroom.

God, I'm still laughing... I'm not looking to go to that expense. It's a large restroom, a hidden noisemaker on a timer should suffice. We have quite a few employees that use it for a hiding place, or maybe they just have an embarassing medical condition.

I don't have recording equipment, but I do remember seeing a cheap MP3 player, about $5.00. Might have to try and find that website again. Still think there is a simple transistor oscillator circuit that would work well enough. I'll keep looking, will post whatever I find.

Why don't you just buy (or trash pick) a cheap and nasty cassette player?