At the moment, I'm addicted to playing the drums for Pearl Jam's Ten on Rock Band. Addicted. Even when I'm stuck working, I'm banging out a sort of quasi-rhythm on my desk, my steering wheel or anything else that lands beneath my hands. With this shirt, I'd actually get some proper drum sounds.
There are four drums printed on the shirt, and each one makes a different bongo sound when you tap it with your hands. Sure, not too many Rock Band tracks actually play the bongos, but you get the idea.
The shirt runs on four AAA batteries, and has a built-in speaker. It's machine washable, so long as you take out the electronic bits, and it costs $60 from Latestbuy.