alt Hacker NewsI don't think anyone is suggesting that it's not fine to eventually look up the answer to the question. But chatting about it before it gets to that point, and exhausting your guesses is much more fun than someone looking up answers to every question someone poses that doesn't have an obvious answer within a few seconds.
Then formulate it as a conversation starter not as explicit question like was done here. Only a buzzkill makes such explicit conversation starters. Unless it is a trivia night...
"Remember that movie where" or "remember oh that guy who was in that movie" would both imply this. "Who was the actor in oh that movie where" is clearly a cry for exact answer as quickly as possible.