I'm afraid it's not just boys. I was loudly abused in Sainsbury's Forest Hill a few weeks ago by a young woman. You may recall the shop has pillars dividing some of the aisles towards the back and I was between a pillar and a shelf looking for something. A woman with a buggy asked me to move which I did willingly and then another young woman asked me to move. I asked her if she couldn't go round me and she said "No you stupid fat cow" (although there was plenty of room for her to go the other side of the pillar). I was taken aback and moved away but then came back (by which time she was just standing speaking on her mobile) and said she should mind her manners. "What do you mean - I said excuse me" she replied.
Still my youngest put it in perspective: "You may be fat but you're certainly not stupid Mum."