Place it just after the confusing moment, not before it, so the reaction answers what viewers just saw. Follow it with a Vine Boom to punctuate the moment, or lead into it with a Dun Dun Dun when the setup needs more tension first.
Über diesen Sound
This is an 11-second voice clip built around the question what the heck is going on, spoken in a baffled tone that keeps the confusion front and centre. It feels bewildered, funny and slightly exasperated, like reacting in real time to something that makes no sense at all. That plain, direct confusion is what makes it easy to reuse whenever a situation turns strange.