In this Guardian article, a victim explains the experience:
Earlier this month James Silver, 34, a freelance journalist, was attacked while jogging on the South Bank in London. While one youth blocked his path, another hit him with a rolled-up magazine.
When he spun around another teenager - who had been hiding behind nearby scaffolding - leapt out and hit him hard in the head. When he staggered to his feet he noticed the rest of the gang were jeering and pointing their mobile phones at him.
Silver admits that while the attack left his "ego smarting" he did not think it worth reporting. "At the end of the day I was unharmed but it was pretty shocking at the time," he said. "The worry is that while the bulk of the attacks are trivial, some of these youths could be carrying knives."
Cramer doesn't make the obvious connection to the 2nd Amendment issue, though. Imagine if Silver had been carrying. When the teenager punches him in the head, Silver pulls out a 9mm and shoots the kid in the face. His little friends all capture it on video. Now that would be hilarious.
Come to think of it, maybe concealed carry laws are why "happy slapping" hasn't caught on in the U.S.!