Why do I imagine evil alt-Superman doing an impersonation of Tempus from "Tempus Fugitive"?
EVIL Alt-SUPERMAN: I'm Clark /puts on glasses/
CANON LOIS:

Say, what?
EVIL Alt-SUPERMAN: /removes glasses/ I'm Superman. /puts on glasses/ I'm Clark. /removes glasses/ I'm Superman.
CANON LOIS: Oh, my....
EVIL Alt-SUPERMAN: /puts on glasses/ I'm Clark. /removes glasses/ I'm Superman. This is fun. I could do this all day. In fact, I think I will. Where shall I start? How about Perry White? Oh, wait! What about those nice people from Intergang? Wouldn't they love to know the truth? The Churches, right? Too bad Lex Luthor's dead. He'd get a kick out of this. I know! Let's travel back in time and have him survive that cave-in.
***
Of course, this works better if Lois doesn't know and since the rules state that it's S4 or later... But that'd sure be funny.