Place it at the end of a scene where a request is made, so the refusal lands as the punchline. Lead into it with No No Wait Wait when someone is pestering the speaker first, or follow it with Damn to underline the reaction from the person who was turned down.
Über diesen Sound
This is a very short spoken clip, lasting about 1.7 seconds, in which a voice delivers the Spanish phrase 'ando ocupao', meaning 'I'm busy', in a casual, clipped tone. It feels playful and dismissive rather than rude, like a quick brush-off said with a grin. The delivery makes it work as a lighthearted way to say you are occupied without starting a longer conversation.