J.T.
My 3 year old started this at 2. So in public, you warn her once, if she is on the floor, you pick her up, tell her this is bad behavoir and you are taking her to the car. Leave behind the food, get up from where ever you are & leave, leave that shopping cart (if it is full of food, push it to a person that works there, apoligize for leaving it but you have a daughter that is miss behaving she has to go to the car) and do it. No one will think any less of you. All mama's have had days like that & we just feel sorry for you and understand. I did this in the middle of lunch with some friends, at the grocery store, the library and even at a zoo outing. She misbehaved & we left. If I wasn't driving I took her outside, found a place to sit & let held on to her tight as she threw the fit. She still has metldowns but if I say, stop misbehaving or we will leave... she does. She knows we will & will not go back. Good luck.