Flip flops?

I am walking around my house this morning wearing a pair of "flip-flops" and I got thinking about how they got their name...

I am assuming the name comes from the sound they make as they slap against your feet when walking, and in that case unless you walk with a decided limp, I think they are better called "flip-flips" or "flop-flops". I know when I walk in them, both feet make the same sound and I would describe it as definite FLIP!

What do you think?

Wikepedia was no help at all in this investigation, by the way.