Mimi's right. Plus- he's the BOSS, right? Doesn't that mean he is supposed to handle tricky situations and employee relations as part of his job?? He gets paid to keep things running smoothly and efficiently in the work place. You've already done your part by asking her/them politely to stop, which both gum snapping women seem to have completely ignored. Let the gum snappers now have to tell the BOSS that they'll just keep doing as they please.