Perhaps, Sir, It Is You Who Needs to Grow Up
I am still so mad about this that I have to rant or explode.( Pro-tip: The six-year-old has an excuse for acting like a six-year-old. )
TL;DR. I get that it can be an inconvenience to adults to travel on a plane where there are also children. And I also get that people pick out seats with extra leg room for a reason and therefore like to keep them. But when you're an asshole to a little boy who is non-verbal, and whose heinous crime was to cause you to move your entitled ass two feet over from an aisle to a window seat, I can't help but think that the person who needs to grow up is you.