Grabbing toys from child

OK, I have a dilemma I'm hoping that other moms can help with...

We want to teach our kids not to grab toys from other kids, right? So what do we do when we ask our kids to give us a toy or put it down and they REFUSE (no matter what you say) but you need to leave store or you need to feed them lunch and don't want food to get all over their beloved teddy. Do you just grab the toy from them and hear them scream? Doesn't this teach them to grab toys from other kids?