Occasionally I have done it but it is most likely a drink of water or I have used a tissue or a wipe if I forgot mine.
With 3 under 3.5 am in and out of the shop as quickly as I can...I feed them before we go so don't take snacks and they don't eat as we go around.
Though when I buy polony I will asked for a few slices to be left out (after it is weighed) and the kids will eat that...but you pay for it at the deli counter not the checkout.
I am fortunate enough that none of my little ones are tantrum chuckers so I don't really have to contend with that and I make sure I avoid the lolly isle so they aren't tempted.
I am also a very picky packer and will pack things on the conveyor in the order they should be packed...my XDH just used to just throw them on the counter in no order and it used to bug me no end :lol:

