Sometimes my dog Alex stops right in his tracks. Either he's bored of walking or he's scared of something. I usually just tug at his leash, and after an eighth-note of struggle he continues along happily.
Today, right as we were about to cross Hart Street, Alex stopped in his tracks. I was about ready to tug at his leash... some little kid (no taller than Alex) appeared out of nowhere and was giving my dog the biggest hug I've ever seen.
I stopped too. My kinetic energy was translated to heat by friction.