I used to copy clearances onto random bits of scrap paper, but a while ago I started keeping a notepad for them. That way I can look back and see what clearance I got last time, and can keep track of silly conversations for you all. Here are a few.
From a crew advised of VFR traffic and still looking for the VFR:
ATC: Mooseflight 123, maintain 6000', advise prior to descent.
Pilot: Maintain 6000, advise prior to descent, Mooseflight 123.
Several minutes later
ATC: Mooseflight 123, say altitude
Pilot: Descending through 4500'
ATC: Didn't we agree that you were going to advise prior to descent?
Pilot: Sorry about that.
"We've got all our Christmas lights on."
And then there's the controllers who like to give instructions to crews that seem to be having difficulty.
ATC: Swan One, contact tower 123.4
Pilot: Over to Tower 123.4, Swan One.
Pilot: Tower, Swan One, out of 5000' with Juliet.
ATC: Still with Centre. You have to push the little button to get 123.4
The controller is referring to the type of a radio with an active frequency and a standby frequency. To swap the two you have to push a button. Half the time the button double clicks, so you end up on the same frequency you started, and if you don't look at the display, you miss it, and embarrass yourself like the guy above.