One of my father's Stapelias. This one really stinks like a dead carp. These guys help control flies as they smell like rotting meat. They trick carrion flies into thinking the flower is rotting meat and they lay their eggs on them. The maggots die without real meat for food. I wanted to try getting a time lapse of this one opening but after days of waiting it opened in about half an hour.
Edit: Since a few people have asked, the purpose of the smell is to attract flies for pollination. It's only a few flies that actually get tricked enough to think it's really meat and lay eggs. Stupid flies.