Place it after the confusing action is shown, then follow it with the Bruh sound for a second reaction, and finish with the Emotional Damage sound when the fallout arrives.
About this sound
This 35-second clip centres on the baffled question in its title, asking what Didi Blad is doing, and stretches it out long enough for the confusion to sink in. It feels bemused and mock-exasperated, like watching someone act in a way that defies any sensible explanation. The drawn-out questioning makes the disbelief feel funnier the longer it goes on, turning a simple reaction into a running joke.