I looks like someone throwing one of those kids paddling pools with the lids onprobably with a kid inside attached to the rope
(
taters Bah weep grahnah weep ninibong,
Fri 30 Mar 2012, 23:04,
archived)
there's a reason for that*listens for sound of small children banging on lid*
( Van Da Graph is sufferng wth an intermttent 'i' key,
Sat 31 Mar 2012, 0:10,
archived)