Place it at the peak of the grab in an edit, just as the hand takes the item, then follow with the chase sound to keep the joke moving. A shocked reaction beforehand sets up the accusation, while a laugh at the end lets everyone know it was only a prank.
Über diesen Sound
This is a short, urgent shout of 'Stop! Thief!' in a sharp, alarmed human voice, lasting just over two and a half seconds. It lands as a burst of mock panic, funny and accusatory at once, like catching someone red-handed in the middle of a joke. The sudden, high-energy delivery makes a small theft feel dramatic, turning an ordinary grab into a moment everyone notices.