recently I've come across a couple of instances where marvel characters have directly referenced DC characters or events. They're kinda funny. The first one is funny, after defeating the Brood that were gestating in Kitty Pryde, Tony Stark realizes her phasing ability can short circuit his armor.
The second one is Deadpool failing to make a simple jump from one building to another.
The third is Mystique referencing the infamous "Girlfriend in the Fridge" incident from Green Lantern.
I think it's hilarious that Marvel can poke fun and admit DC exists in a roundabout way and cool the writers snuck those references in.