Okay, you can't really answer this question. I'm very much on the side of yes - I once knew a pony who would toss people into mud puddles if, and only if, they got on him wearing white breeches.
Horses do sometimes seem to do things just because they're "funny." As a social animal, they have a strong sense of play, and they're capable of recognizing human laughter as, well, a reaction and probably a positive one. So if you think a horse has done something to make you laugh - who knows, maybe they did.