The Bucket of DOOM!
Don't let the Bucket's unimposing, non-threatening appearance fool you. A closer look (but don't get too close!) will reveal it's evil secret.
Heed the warning or perish!
It must have happened to someone or the warning wouldn't be there. Almost certainly, it's origin does not derive from the preemptive measures taken by a manufacturer with an irrational fear of litigation.
Even Nanuq is wary of the Bucket of DOOM. Animals have a sixth sense about these things.
Be afraid. Be very afraid. And whatever you do, don't kick the bucket.