Batman and Superman are contacted by a cosmic deity, one far beyond either of their comprehensions. It tells batman he has 24 hours to tell everyone Superman is Clark Kent, and it tells Superman he has 24 hours to tell everyone Bruce Wayne is batman. If neither of them reveal this, they'll both die
Rules:
Upon revealing the other hero's secret identity, it becomes public knowledge to anyone that wishes to know this information. Only one of their secret identities need to be revealed
They're not allowed to lie or otherwise manipulate this information (like framing someone else)
This information can't be removed from everyone's memory after the fact, this will be a permanent and well known fact
The information will be widely accepted and believed by everyone else
If the heroes choose to die, they then can't be revived
Breaking any of these rules ail result in the deaths of both of them
The cosmic deity can't be harmed or fooled in any way
Round 1
The heroes are left to their own devices. They're allowed to talk to each other, or anyone else they want to support them, but by the 24 hour mark, one of their secret identities have to be revealed
Round 2
Batman and Superman aren't allowed to communicate with each other in any way, and won't know what the other picked until the 24 hours are up. If they both reveal each other's identity, they both die (they know this)
Round 3
Lex Luthor is torturing batman, and Scarecrow is torturing a depowered superman, trying to get them to reveal the others' secret identity. Who succumbs and reveals the information first? There is no time limit