Crossovers or mash-ups are mixing two or more concepts, shows, movies, etc. together for humor or to make you think. For other crossover posts, type "crossover" into the search block of my home page. Enjoy!
The ones on the bottom you can't read but I'll tell you what they say: the first one to the left, "this sucks" (captain America), then middle one,"I miss my daddy" (green goblin), the last one, "I never met my parents" (super man)