Swearing & vocabulary

Evening all So I have a rather clever little 19 month old. He can count to 20, knows his alphabet, knows lots of songs, can ask for things in short sentences however picked up on a naughty word and now won’t stop saying it 🙈🙈 me or my partner accidentally said F Sake a while ago and now our little one has included it in his vocabulary… today he dropped something and said it 🙈 so he isn’t even repeating it, he kind of understands the context to use it… he has an amazing memory and picks up things sooo fast. We have tried to ignore it, tried to say other words like duck, and tried telling him not to say it but it keeps coming when he is frustrated 🙈 any advice?! Thank you