thanks for asking... I didn't know this either!
Besides playing with the bucket, it's a handy way to separate corpses for looting. If you happen to kill a bunch and they all land in one heap, it's difficult to
find the one that hasn't been looted yet. So you hold the E and move the corpses (one at a time) to expose the ones on the bottom.
What bugs me is that I can only move stuff that has a label (like bucket) but not the other stuff cluttering up the floor (mostly bones). I cannot pick it up,
but I can kick it - making noise to attract unwanted attention.