Here goes my 10 cents:
Glider: TWR, request crossing CTR
TWR: hold position and altitude
Glider: uhm, we're a glider
TWR: Ah, ok, cleared to cross CTR
And one for the oldies (surprised no one posted it already)
Not sure if it is authentic, but it's funny to me.
American airliner vacated runway at Frankfurt and holds on taxi way, pilots are looking for their gate.
FRA TWR: xxx, why are you stopping?
xxx: we can't find the gate
FRA TWR (irritated): it's not that difficult is it? Haven't you been here before?
xxx: well, yes I have, some 65 years ago, but I didn't stop here!
Similar typical EU joke:
German airspace, small aircraft starts transmitting in German
ATC: xxx, repeat your request in English
plane: why sjould I speaka Engelish? I am a Djerman in a Djerman plane in Djerman airspace; why sjould I speaka Engelish?
Voice over radio in perfect English: Because you lost the bloody war!