Don't know if you've seen this one, but it's great. The hapless victims of this harmless prank are surprised at the end. It's unexpected. The mind needs to comprehend what it's witnessing, put it into context. When the predicable happens, it's mundane, forgettable.
How often do you deliver what's expected? Sometimes, that's appropriate. But it's also appropriate to push past the boundary of your audience's anticipation of what's expected into their imaginations. How often can you make them laugh, cry, gasp, cheer?