I can hardly type for laughing.
Mr Paw is upstairs doing the whole u-bend thing now while I'm down here eating my tea.
He just came down to get something longer to poke about with (fnar) and said in passing he's made of fail.
He unscrewed the pipey thing, and it was full of water, obviously, so he emptied it down the sink
I can't stop laughing. I'm actually crying now.