Did a pre-flight once on a Cessna that was normally parked out in the open. Bent down in front, as one does, to check that no bird had built its nest on the engine block. The moment I did so, an explosion of brown feathers erupted in front of me and I had a momentary glimpse of a razor-sharp yellow bill whiz past my left eyeball at a distance of about half a millimeter, doing a quite incredible rate of knots. How I wasn't blinded by the bloody thing, God alone knows.
Nowadays I slap the side of the cowling loudly a couple of times before bending down.