Port-a-Potties are the worst. They're especially bad at festivals, where they've been used by thousands of people. For one woman at a music and beer festival in the UK last weekend, her Port-a-Potty experience became infinitely worse when the Port-a-Potty began to move while she was on the toilet. (No, it didn't move spontaneously, like the Port-a-Potty in this gif.)

Staff moved the Port-a-Potties because of a security incident, but obviously failed to check if anybody was in there.