dark side of the moon

i was in mid-rant at a boy today when a colleague came into my classroom to give me half a puff-ball mushroom. instantly my mood changed - how mercurial am i?
i've been totally knackered today after the sailing trip and have been on a very short fuse. I play fair with the boys and warn them not to play up - but one decided to ignore my warning! every class afterwards was as good as gold after that - obviously the word got round!