Once i had invited one of my female colleagues to a party. The great thing about this party was, that we were a few who wanted to get a night never to forget, so we baked a nice choklade cake with a lot of marijuana.

Well.. my colleague ate some of the cake, and after a little while she started to cry without any reason. The day after she told me that she wasn't upset at anything, and as Nausicaa said, just felt like it.

It's really strange, and it's also the only 'crying situation' I've experienced.