In the recent Justice League movie, Barry Allen, AKA The Flash, describes himself as a "long-haired, very attractive Jewish boy". How do we reconcile that? The Jewish part, natch.
There is absolutely nothing in the Allen backstory, be it in the movie or numerous comic books, to suggest that he is Jewish. In fact, he is rather obviously goyishe. (Trust us, we're pretty good at identifying latent Jewishness, especially in comic book characters. This is not one of those cases.)
So what could it be? Perhaps this movie Barry Allen comes from some parallel dimension, or Bizzaro World? (A thought: are there Jews in Bizzaro World? And if so, who do these Bizzaro Jews worship? Let's stop before we dive into this wormhole any deeper.)
Actually, the answer is quite simple: the line wasn't in the script. Ezra Miller, the actor who plays Barry Allen, ad-libbed it, and the director left it in as a joke. Why did Miller insert it? He was describing himself: he is Jewish, not the Flash. (He is clearly not long-haired either!)
Now, the "very attractive" part? We'll leave that for you to reconcile, dear reader.
(Editor's update, 2022: Seems like in real life, this Flash is a creep.)