I think Karen was going to get whacked too. As she got nearer the shop you could see her getting more and more scared and anxious, she realised if she went in the shop she'd get whacked. When she looks up to Jimmy at the top of the street and shouts something about not having time to look and she'd look later,and jumps in her car, his face says it all what an evil look like he's really peed off with her for cottoning on!