This pic is just… sad.

They are married and have a kid, but Senpai is unemployed for whatever reason. Nagatoro has a diploma but has to work at 7/11 to make ends meet. Their house is run down, there's cracks and duct tape everywhere since they can't replace or properly fix it 'cause no money (including Senpai's own glasses). Now they fight and their little girl watches sadly, even having to turn to her imaginary friend (look at the shadow) since mommy is too busy yelling at daddy for being dead weight.

Fuck, this is just a drawing. Why does it hurt like that ?

So I think the joke is that even through Senpai was an Honor Student back in the day, his Art Degree is basically useless.

Also I'm pretty sure that's not an Imaginary friend, and is actually a Shadow demon they summoned for whatever reason with the Ouija board in her hands hence the foot prints on the ceiling cuz the place is haunted.