Now that we have all grown (and groaned) out of viola jokes, there's a new breed of humor afloat. Lying in the very same range as the viola (minus the C string) is the countertenor, and tucked away on Andreas Scholl's website is a page of Countertenor Jokes!
Here's a taste:
How many countertenors does it take to change a lightbulb?
Two. One to screw it in and the other to say "Isn't that a little high for you?"
I have to warn you that the site is rather tasteless and is peppered with crude gif animation, but I'm sure that you will find something to make you smile. I did.