OOOOHH! Can I join in?
I used to have a washboard of my very own. (Kinda fits in with the drummin' ya know.) My fave was one of those neat "sqwak horns you find in the Western Auto, or used to before they mad 'em outta plastic.
Also, consider a swazzle. They are hard to buy, but easy to make. If ya' don't know what one is, you may not wanna try one, though.
Mikal