[cloudmountain]

chunder bucket

It IS a preferable euphemism.

[cripplecreek]

It’s from a term used aboard ships. If the sailor was below deck and had to throw up or take a dump he used a bucket. When they dumped the bucket overboard or out a porthole they yelled “Watch under” and that was shortened to chunder.

I heard it on an episode of “Turn” a few weeks back and went looking.

[lyby]

chunder bucket

It IS a preferable euphemism.
*****

However preferable, it does lack the alliteration of the crude colloquialism. ;-)