Shouldn't be a long thread, but since there are quite a few different cultures represented here, I thought it might be interesting to see what other people call them. I can remember my mother calling them "slides" when I was young.
Flip-flops where I'm from in Scotland. Thongs where I live in Australia - but they have to be the ones that go between the toes. The ones that don't get called slides here. I have a friend from New Zealand who tells me they call them jandals over there, which I think is funny.
My Marine drill instructor referred to running shoes as "go fasters" (in reference to fighter planes) and flip flops as "go slowers".
Thongs Flippers Mud-Flickers (There are other version of this one, but this one is the lesser vulgar of the ones I know/have heard it referred to as, I am sure you can use your imagination to think what it really was.) Slappers/slaps (from the sound they make) Dressing Shoes But my favourite, which comes from french is: "Écrase bouse" Meaning: "Cow-pat Crushers".