I won't bother with any kind of description, as Old Webster has already taken care of that. I might add, however, that they are usually round.
Ah, the tambourine. An instrument I play well. Too well, some might say, and they would be right. You see, some years ago I made a deal. A deal with the Devil. That's right, I sold my soul for tambourine skillz. I can't say I regret it either. I have a friend who's the singer in a band, and sometimes when they're playing he'll ask me and Sally to come up and just kinda stand behind him and keep the beat. When there's a band playing near me and their tambourine player is sick or something, people know to call me because I am the best.
Everybody knows the tambourine players get all the chicks. I can't keep them off of me. They ask me to slap their asses with my tambourine. The problem with women though is that they always want you to defend their honor and stuff. Like, this one time, I got roped into this situation with a pair of Latvian prostitutes and a Mexican Mariachi gang. We had an epic tambourine-off and I totally kicked their asses.
Of course, selling your soul to the Devil isn't the only way to get good at tambourine. I mean, you could practice a hell of a lot. However, I recommend signing The Contract. It's worth it in the long run.
Another of Everything's Most Wanted brought to justice.