Brian Earl Spilner said:
It's not even the worst DC movie.
Off the top of my head:
Catwoman
Wonder Woman 1984
Justice League (Theatrical)
Superman 3-4
This is a solid list of steaming piles of crap. But Batman & Robin beats all of them. It beats out Superman IV: The Quest for Peace by a hair.
I should probably rewatch both just to see if my opinion circa 1997 still holds, but damn, I don't want to give my TV a disease.
Edit - have to add that the theatrical release of JL had a damn fine movie at its core, as evidenced by Zach Synder's Justice League, but the hack Joss Whedon just couldn't help himself. How he made The Avengers, and to a lesser degree Age of Ultron, so damn good is beyond me.