Do stop me if I've told you this one before...
[don't stop him, regardless]
I was once marking a set of questions on a tripos paper. They were about nerves, myelinated and non-myelinated if I recall. One of the students had decided to draw a non-myelinated axon, in cross-section.
[Dr Tapp draws a large circle]
And, do you know, he'd been told it was a good idea to label diagrams. So, do you know what he did?
[we know exactly what he did, we've heard this three times already. But Dr Tapp is by now laughing hysterically and it's just too late]
Do you know?
[cut the crap, oldy]
Well, do you?
[come on, this is getting dull]
He didn't know the word 'unmyelinated', so can you guess what he put?
[oh brother, please. by now we've already written the word 'bear' on the sheet of paper but he can't see it. someone in the corner is by now colouring in a large picture of a grizzly bear, but he's not noticed. others start growling subtly]
He put 'bare axon'! But that's not the funny bit, you see!
[oh no, the funny bit's coming up just now - don't worry if you miss it though, it's no great loss]
Most people would spell it 'B A R E'. But this simpleton, do you know how he spelled it?
[three people have already left. anyone who hasn't worked out the punchline yet is really very slow]
He spelled it...
[a long pause while Dr Tapp uses his legendary comic timing and tries to stop his own uncontrollable chortles]
'bear axon'... as in 'B E A R'. You know, the grizzly thing. I was on the verge of writing something amusing on his paper.
[amusing? Dr Tapp?]
But I restrained myself. Anyway....
[Dr Tapp spends the next half hour occasionally muttering the word 'bear' and chuckling quietly]