Not heard by my self, but repeatedly reported by many others:
Erau @ KDAB uses "Riddle" as callsign. Busy day in the area for Riddle a/c and a guy transitioning from Jax calls up "Riddle me this, what the hell is with all the riddles?"
not as good as some others on here, but still somewhat amuzing.
Another one involves a Riddle and a Papa Echo (from nearby Pheonix East, who has a contract with some certain foreigners that generally answer tech support lines) heard on clearance:
"Riddle ### would like to request VFR to the north practice area @ 3k with Charlie/Foxtrot (don't remember the atis)"
clearance starts readback and get's stepped on.... garbled, and then when clearence stops xmit
"uhhhh also uhhh to the north practeece are-eee-ah, uhhh N6969 PaaaPaaa Acho"
Riddle to clearance:
"Riddle ### can we change that to the south practice area"