You think he's getting a little big for his britches now, just wait till he can actually see out the window.
I've seen the way he struts around at daycare, blowing kisses and spit bubbles at all the pretty ladies. And the "Mommy's Little Prince" onesie isn't helping matters. He knows he has the world wrapped around his chubby little booger-crusted finger.
You get him this First Years Booster seat, and I'm telling you, your troubles will have only just begun. Right now, the only thing he has to look at is his own reflection in that head-rest mirror that lights up and plays happy music every time he peers into it, so it's understandable that he believes he's the center of the universe. You might even think that giving him a clear view of the big world outside the car might do him some good, bring him down to earth a little. But you're wrong. So very wrong.
You put him in this First Years Booster, and you'll have given him an eyeful of a whole new world awaiting his total domination. Today it's "I want apple juice" and "cookie, now!" Tomorrow it's "Jeez, woman, where did you learn to parallel park?"
Just don't say we didn't warn you.