Back to the shop when it’s open, see if they like it
+1
But that is my opinion. Others may say leave it, but they probably care less about what others say or do in front of their kids. i would wait till the offender was talking to another customer, then interrupt with a ‘very brief question’ ..Why did you tell me to etc.
Alternatively, go back in, on your own, ask lots of questions, line up lots of stuff to buy, including all the little bits of fiddly stuff. Then when you get to the till, Oooh! just remembered, bloke in here told me something, which i must make sure i do. He told me to **** off, so, I’ll do that. Thanks for the advice.