If you're not keeping up, Justice League is in reshoots (shocker, after Snyder left and Joss Whedon came on). Therefore, our modern Man of Steel, Henry Cavillm is acting in two movies at the same time, and he's legally bound to wear a mustache for his part in what I think is a new Mission Impossible movie.
So, WB is going to film a mustachioed Superman and then digitally remove his cookie duster.
But - what if it were otherwise? Well, the internet went nuts yesterday imagining how great that would be.
And, if you want to do more than imagine it or look at a few MS Paint photo manips, the internet hath provided... (also, The Dug, who sent this to me)