My wife had a birthday party for me that I didn't know about. I was totally taken aback when all my friends showed up.
My wife held a surprise birthday party for me. It was totally unexpected and I was shocked when I came home and so many people were there.
user
That's awesome, I bet you were overjoyed with it!
assistant
I couldn't believe that no one let the cat out of the bag. It must have been hard to plan.
user
You never know if someone is going to slip and spoil it for you, that's true!
assistant