I remember a horror/suspense movie where a group of friend disappear or gets killed one by one, but in the peak of the suspense, at the end, the lead actor enter to a fancy room where everyone is having like a party, everyone was still and then they start clapping, it was all a joke, like an April’s fool joke, which I remembered it was the name but it wasn’t.
April Fool’s Day (1986 or 2008)
The Game (1997)
I second “April Fool’s Day.”