Uh, not to be too gross or gruesome, maybe remind them that the vacuum is not to be used on PEOPLE. There are actually lawsuits out there about males who use the vacuum on, um, PARTS that could be a BIG OWWWIE.
Animals, too. No sucking the kitty's tail up, or water in the tub (eek).
Sorry, occupational hazard. Lawyers are the ones recommending all those warning labels, lol.