Meanings of flopped through in English

Has a copy of the Rules of the Road flopped through your letterbox yet?

Last Tuesday morning a large white envelope flopped through the letter boxes of hundreds of Celtic supporters here.

That prediction has flip- flopped through the week, but it seems likely that amount will indeed fall in the region.

His dreadfully overstimulated brain conjured horrible, sickening pictures: a giant mole, a great bat that flopped through the underbrush rather than flying.

Anthony's overcoat was off before he had fairly entered his room and his coat and vest flopped through the air as Peters shut the door.