Comic Crossover Jokes

I don't mean stories of character from company 'A' meets character from company 'B', more like the in-between jokes.
I'm reading post crisis on infinite Earths Superman, and I saw a bunch of Marvel characters jokes in that title.

Superman v2 #013: Toyman debut in that reboot, and one of his deadly toys is that of Iron Man.

Here's a nice image from Action Comics 659.
The kid in the corner wears a Hulk shirt.

And an image from Superman v2 #50
Fantastic Four joke.


Share the fun pokes you can find, images included for the highest level of fun, please.