For once I really like how this thread develops. And although it it pretty unrelated to WC, that merits another story:
For fantasy multiplayer games, one of my pals decided to go with the nick "Musculus" because he was into bodybuilding and wrestling at that time. He'll never recover from it, because the word means "little mouse" in Latin. Boy did we have a good time.
...only slightly marred by my own choice of "Cayman", which was turned into the obvious.
Nowadays, I fall back to use whatever comes in handy as a callsign (or tester profile, nick, flag) - we've had Teacup, Frame, Biro, Chalk, Ruler (really cheesy, yeah, but I liked the double meaning)... and so on.