I can't remember where I got this from, but it feels deeply correct to me. However it caused a misunderstanding in a chat, and after googling the usage and not finding anything I'm suspecting I might be using it wrong.
So in my mind, given the right context "guess what" can be equivalent to "Oh, interesting, who'd have thought that". Like in
Them: Did you hear about it, Adam and Eve got married today.
Me: Guess what!
So I'm saying "guess what" to express my feeling of surprise, not because I actually want them to guess something. Is this usage valid?