It is possible to die from being hung upside down. The blood makes your brain swell.
In Raidou's case, it hadn't gotten that far. But there was AB-so-LUTELY no blood in his legs. He toppled over backwards, dragging Genma with him into a pile of ropes.
"Genma?" He started to pat the man down, pushing at the flow of his chakra, feeling it out the way a merchant fondles silk. "Genma, Genma, you can't get lost. If you do that, that, I'll. You'll have to hold my hand at all times it'll be the buddy system,"
Genma'd said something, and it registered. "We can't get married, Genma. I don't have any pants. What will our grandchildren think when they look at the album and I have no pants?"