Put it in the bath with some shampoo and warm water. Stomp on it till the water is discoloured, then pull the plug and squish it to get as much as you can out, refill the bath to rinse and do the same. Then squeeze all the water out against an empty bath and hang on the line in a U shape so the stuffing doesn't fall all the to bottom.
I'm going to give that a go. Thanks for starting this thread Curly!