Place it at the exact cut to the surprise, then follow it with MLG Wow for a second, bigger reaction before the scene moves on. For a chase or escape that follows the reveal, bring in Cartoon Chase Music underneath the action to keep the energy moving.
About this sound
Mordecai and Rigby stretch a surprised woah into a long, wobbly cartoon exclamation lasting about nine seconds, their voices rising and falling together in exaggerated disbelief. It feels silly, playful and instantly readable, turning a sudden reveal into a joke without extra dialogue. The reaction comes from Regular Show, the Cartoon Network animated series that debuted in 2010.