Frogs flipping on their back seems to be a fairly common behavior, but not normal. There is no immediate danger to the frog. It is a sign of stress or some sort of danger, either real or perceived. The best remedy is to leave the frog alone for a while in a quiet place. Eventually this behavior will stop when the frog becomes comfortable. I used to be an amphibian keeper at a zoo and it is quite overwhelming when you see 20 frogs on their backNo one seems to know why frogs flip, but it doesn't seem to harm them.