I was crossing a road after just walking past a woman with 2 kids - one kid in the pram she was pushing, the other on foot.
The kid on foot ran across this road, without looking, and a taxi driver had to slam on his brakes to avoid hitting the kid.
The woman yelled "Slow Down, Asshole!".
I was bemused by this; and you know how you always think of the right thing to say AFTER it would have been the right time to say it?
Well I thought to myself, what I should have said in that situation was "Just because your child runs across the street without looking, it's no excuse to call him an asshole!".
I wish I'd said it at the time. The story makes me smile, even now.