Put it just after the battered object appears, as the setup for the reveal, then follow it with a reaction such as You What to sell the disbelief. For a bigger payoff, add DJ Airhorn once the joke has landed, keeping the bucket line first so the reaction and the sting stay in that order.
About this sound
This short clip is a single spoken line asking whether someone wants to see an old rusty bucket, lasting just under four seconds. Its charm comes from the ordinary object and the casual invitation, which land as oddly specific and quietly funny rather than loud or dramatic. It works best as a bemused aside, turning a dull object into a small, unexpected punchline.