Personally , I've had a Kamakazi Pheasant and the herd of black bullocks in the road.
My mate Merv had the best/worst one tho.
Years ago we were riding down the A46 up to the six hills one evening, it was still light, me on me moped the other lads on big british bikes and some japs, Merv came flying past me on his super six, then he started a massive wobble and pulled up.
when we stopped next to him it was a horrid sight,
Merv had a full face helmet but never a visor, in his helmet was a mess of feathers and snot, he was wailing like hell.
A sparrow had flown across in front of him and splatted into his eye, he took of his helmet and there was blood n snot everywhere on being cleaned up he had no damage well apart from a very blood shot eye, the bird didn't fair so well.
Merv always had a visor after that one.