And by weird, I mean the kind of insanity that would drive normal people to their breaking point as they question reality. The kind where you question what drugs the writers were on to come up with that, or worry for their mental health.

Things like the Peter Parker Clone Saga. Or the scene where he is turned into a spider, somehow gets pregnant, then dies and then basically gives birth to himself by bursting from the body. Or the time Jason Todd gained the power to turn into a tentacle monster and ate a guy. Or just... Most of Supergirl's history apparently. (I have only brushed the surface, but DC's edict make Superman the last Kryptonian led to some convoluted explanations to continue using legacy Kryptonian characters. Also, her horse had a raging crush on her and is technically an ex thanks to human-transformation shenanigans.)

Mainly thinking of DC and Marvel, but I'm open to other long-running comic book universes. Because with enough time, writers have to get creative to fill in issues, and stuff gets WEIRD.