NCd - embarrassed and unsure
Child just said "you have sex with your brother"
And collapsed into giggles. I've said they have no idea what that means and it's really naughty to say it and asked where they heard it
They said "coronation street" ??? I don't watch it very often and can't remember that storyline! They're normally in bed when I watch it also 
They've run off yelling "you have sex"
I live in a small flat, neighbors must be really concerned or amused
I have no idea what to do! 5 is too young for the "talk"
I'm single... I'm not having sex so not even sure how/where this has come from.
Please advise a very embarrassed shocked mum!