It's getting out of control now and I don't know what to do. He picks up everything, despite our best efforts we obviously failed somewhere along the line He started saying it the odd time (shit or fuck), and I ignored. It stopped, then started, I ignored again, it got worse so I started taking toys off him, putting him in room for a few mins but it's getting so much worse. He seems to say it without thinking, and also looking at me for effect. He has started singing the words, even singing "two little birds, sitting on a wall, one named shit and one named fuck..." in the bath I have come down hard, making him leave his cousins house when he just didn't stop (after BIL even helped by telling him off, taking his toy away etc.) (we went back in, he said he was sorry, wouldn't say naughty words again, but he did really think we were leaving). I have tried everything, bribery, being hard, just talking to him calmly but sometimes it just goes on and on. Please tell me it's a stage alot of toddlers go through, I feel like 1) I have failed massively for letting him learn these words and 2) it will just carry on and he will be a 4/5 year old who is aggressive and rude. He is 3.7 by the way and too smart for his own good (I said he could have his biscuit he made at school after his dinner and bath, and kept reminding him also if he didn't say a naughty word. I then gave it to him and he told me he had said fuck on the sofa. Is it just an attention thing?)