When your tube sock(s) hang off the end off your foot 1/2 way and they fop around.

When children's sock(s) slide/fall down.

NOT to the point of falling off though, just 1/2 way.
'When I got out of bed this morning my socks were flipper-slippers!'

'That baby's got on a flipper-slipper.'

'Flipper-slippers are fun to slide on the kitchen floor in!'
by Patsea Chema October 1, 2011
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