it's funny as hell when kids cuss, not that it should be encouraged. when that katy perry song was playing all the time my daughter used to walk around all the time singing it, even out in public. "you pee your pants, like a BITCH"
another thing that she got stuck on a year or 2 ago was saying "what in the hell is going on here?!" after hearing my wife say it when her phone was messing up. i think part of it is kids find a kind of humor in seeing us get frustrated so it makes a greater impression on them
anyway kids are gonna say shit, and there's really no reason to come down on them hard about it. when i was growing up my mom would get super pissed if any of us said something sucked, so we started saying that things hoovered instead. what's vastly more important than restricting the words kids use is nurturing their usage OF words. they are much more in tune with the spirit behind words and phrases than their actual meaning so it's less about watching what you say than keeping tabs on what you're meaning in saying it. just keep in mind that harsh meaning impresses harshly. you'll learn a lot about yourself along the way, kids are like the most unavoidable behavioral mirrors.