How do you deal with a tantrum when you're out in public?

2 words......abort mission.

I walk away and tell her see ya later, mom's leaving. I just go to the next aisle or whatever and listen to hear if she stopped. if that doesnt work i take whatever toy or food or whatever we got her and put it back. we leave the store without getting anything no matter if she stopped or not. it teachs her that only if she behaves the whole time does she get anything

I allow them to take one toy with us to keep them entertained when I take them out. If they have a tantrum, I calmly remove them from the situation until they calm down.