Hey, it's
Calendar Man's birthday! (even though it doesn't say that on the probably-no-longer-canonical
Super DC 1976 Calendar).
Happy birthday to you, happy birthday to you, happy birthday dear Julian, happy birthday...y'see, I can sing that song because now, unlike Batman,
it's in the public domain.
from Injustice 2 #3 (DC digital comic, April 2017), script by Tom Taylor, pencils by Bruno Redondo, inks by Juan Albarran, colors by Rex Lokus, letters by Wes Abbott
Oh, and I should probably point out that it's a dystopic alternative future where Superman killed the Joker and Batman has raised a rebellion against him and so both Supes and Bats kill people now and also Harley Quinn and Green Arrow had a meet cute. (It's all true!)\
Nooooo! Clock King! Magpie! Killer Moth! Wonder Bread Man!
So honestly, I wouldn't invite Future Murder Batman to your birthday party, but if you do, at least remember that he brings fireworks.