part of "The Farmer in the Dell" for the bathroom:

Flush the toilet close the lid, Flush the toilet close the lid,
High-Ho the Dairy-Oh, Flush the toilet close the lid!

then substitute:

Now we wash our hands...
&
Turn off the light and shut the door...

until we're out of the room.

Although Lynn's is funnier.

And for eating we sing to the tune "If You're Happy And You Know It":

Wipe your mouth on the napkin, if you please,
Wipe your mouth on the napkin, if you please,
Wipe your mouth on the napkin, it will keep your sleeve so clean,
Wipe your mouth on the napkin, if you please.

ALSO:

Wipe you fingers on the napkin, not your shirt...

Wipe you nose on a kleenex, not on me...

and so on, depending on the faux pas.
______

"If you want yor children to be bright, read them fairytales-- if you want them to be brilliant, read them even more fairytales" Albert Einstein