This strip makes me cringe, because I nearly knocked my cousin's teeth out this same way when I was ~6.
But before we get to that, why does Mike look so horrified at Merrie's first unsuccessful attempt? The kid's two and a half feet tall---what does he think is going to happen?
And then his smug look while he's demontrating. I can just hear him thinking, "Yeah, they'll keep making more complex video games, at which both Merrie and Robin will be able to kick my ass...but yo-yo development ain't going anywhere, and I will forever be the champ!"
But he should have curbed his bragging. Have her stand on something so she can master the basic up-and-down maneuver, before she gets into the "ferris wheel" or whatever that move is called!
And what a weird stance when he gets hit! It looks like he was about to bust out some disco moves. And the impact seems to have removed much of his face. What's the psychological implication of Lynn's recent portrayal of faceless people?
I think there's a metaphor in this, too: every female Mike comes in contact with gives him a black eye, literally or figuratively, maybe? Check the tear dripping from his eye. And in the last panel, why is the yo-yo sitting right there for Merrie to grab? And, could Dee's arms be any skinnier?