I've heard them referred to as thongs, flip flops, shower shoes, jap flaps, rubber sandals, beach sandals, beach shoes. The thong thing is funny now that you mention it.
I don't mind them. Sometimes I wish I had a pair. I never think to buy any when I see them though.
You may optionally give an explanation for why this post was reported, which will be sent to the moderators along with the report. This can help the moderator to understand why you reported the post.