Not just any snake..an eastern diamondback rattlesnake. One that size is very deadly…and down south…very common, especially this time of year. Somebody left a cleanout open outside and somebody else decided to go for a swim and see what's up. Not common, but not rare either. Sometimes they're smelling rats in the pipes and investigating. If that happened in the dark and he bit someone on the ass (which can't be tourniqueted) it might be game over.