SUPERMAN: Oh no! Mxyzsptlk and Loki have teamed up, Earth's population is slowly morphing into squirrels!
THOR: Aye! We daren't delay our retaliation1 But soft! We must also comply with yon "Superhero Crossover Act of 1931" which states in section 1 paragraph 9: "In the event of a team up between two parties of parallel dimensions, said meeting must be accompanied by an initial misunderstanding and a physical altercation"
THOR: HAVE AT THEE SPINELESS KNAVE!