Jamie (one of our tutors) came down to breakfast one morning, stood in the breakfast queue and said 'I had a dream that everyone was mocking me.' All of us near him started laughing and then he said 'My dream's coming true!' and we laughed more.
The funniest thing about it was the deadpan look on his face when he said it, and the fact that there wasn't even a pause or nervous laughter, we just all started giggling at once.
Obviously I have not been giggling over that all the way home from rehearsal XD