To be fair, here are some clarinet jokes:
Is there any difference between the sound of a clarinet and that of a cat in heat?
Of course there is, but only if the cat's in good health.
How many clarinetists does it take to change a lightbulb?
Only one, but he'll go through a whole box of bulbs before he finds just the right one.
What's the definition of a nerd?
Someone who owns his own alto clarinet.
What's the purpose of the bell on a bass clarinet?
Storing the ashes from the rest of the instrument.
How do you know when a clarinet player is at your house?
They don't know where to enter and what key to use.
What's the difference between a clarinet solo and scraping your nails down the blackboard?
Vibrato.
How do you stop an oboe from being stolen?
Put it in a clarinet case.
How do you make a saxophone sound like a clarinet?
Miss a lot of notes...
What do call a line setup by clarinets?
A circle
And here is a site with more jokes (in general), though they're not all clarinet jokes...just music jokes.
http://www.geocities.com/clarinet_girl7537/jokes.html