I don't know whether to be worried or not. My 6 yr old when he's been play fighting with his little brother (4 yrs) has said things like 'right I'm going to put my penis on your bum'. Now, his actions aren't mimicking something sexual as such but it's said in a jokey way. Earlier he was writing hearts on a birthday card, realised it looked like a bum then said laughing 'I'm drawing a penis on the bum'. I have parental controls and I limit YouTube but I'm wondering if he's seen something on there and is copying. I've asked him once or twice and he just says he hasn't seen or heard it anywhere, it's a joke. I've also chatted to him about appropriate behaviour boundaries etc. I'm wondering if he's seen something or if this is just normal kid stuff. Anyone had any similar experiences? Thanks