Cat doesn’t like the way your friends sister was playing with it then. Notice that the tail is thicker than usual - cats make their hair stick up when annoyed/frightened because it makes them seem bigger and more threatening to other animals; if you see two cats fight, both fluff up and wail at each other to intimidates the other into backing down.

They don’t usually fluff up just the tail and it usually means “feeling powerless and annoyed” so could be as simple as not liking the way it was petted, or as complicated as feeling like it has just been manhandled.

Edit: also thump thump thump beating of tail against ground means he’s starting for a fight. You can tell this is unusual because it’s not comfortable for them to whack their tail against the ground repeatedly. Basically just wants space, but also seems not that annoyed with you nearby, as if your presence keeps the other human away from annoying him/her.

You can relate this to a stegosaurus or a scorpion, creatures who also fight with their tail.