Civil Aviation Humor

Having completed my first solo on Bulldogs, I taxied back to ATC to pick up my instructor, as he was watching me from the tower.

ATC: Uniform 45, can you confirm that you are behind the tower?
Instructor: Yes, Uniform 45.
ATC: Oh right, it's just we couldn't see you behind the buildings.

*Silence*

Instructor: Stealth...