There's a lot of legitimate reasons to be afraid of roller coasters. Heights, construction, harnesses.
But you NEVER have to be afraid of crashing into another roller coaster.
Birds, on the other hand? Ya, apparently you need to be afraid of them. Just ask this guy, who was on a roller coaster at Paloma Ferrari Land in Italy. The Red Force coaster ride was going great, until this bird decided the ride was in his way.
The poor guy gets completely smacked in the face by the bird, leaving his face pretty bloodied.
You have to check it out for yourself. It's both funny and terrifying.