The first time I took the (now) missus to a game in the early 90s - might have been a cold afternoon at Oxford as that was close to us at the time - and we found a quiet spot on the away terraces about 15 minutes before kick-off, with most fans talking amongst themselves waiting for things to commence. Suddenly, right behind us, came the ear splitting shout "Green Arrrrrrrrrrrrrrmy!". The other half jumped out of her skin and threw her coffee everywhere! Needless to say I was more amused than she was!
After that we always made sure we weren't standing too close to Noddy whenever I took her to a match, to save her nerves! What a character he was...
As for strange fans, I always remember the self-styled Bruce Forsyth Appreciation Society who would turn up with bits of carpets on their heads at various "hair" related grounds (Wycombe and Barnet were the two I saw them at IIRC).