Hell, all of the epilogue is pretty funny. From the guy who asks Bruce for Ketchup, the Spectre's reaction to a "Spectre Platter", to Bruce needing a drink once Wonder Woman and Superman break the news to him... considering it's the epilogue of a rather tragic epic story, it's incredibly funny.
Waiter: Hello, I'm Robin.
Bruce: Of course you are.
The cake definitely goes to Batman for being the grumpy old snarker he has been all his life.
This entire exchange:
"It's awfully crowded here," Clark noted. "You're sure we won't be recognized?"
"Hardly likely," she replied, still examining the menu with its cheesy names for the meals. "In the first place, you wrote the book on secret identities..."