[I can't decide whether this thought-experiment has any policy relevance. I hope not, but who knows what the future will bring? It came to my mind after reading a (more policy-relevant) post by Simon Wren-Lewis.]
1. Helicopter money is when the central bank prints money and puts it in people's pockets. Vacuum-cleaner money is the exact opposite; it's when the central bank takes money out of people's pockets and burns it.
2. Paying 5% interest on holding money is when the central bank pays you $5 per year for every $100 you have in your pocket (or in your account at the central bank). A 5% tax on holding money is a negative 5% interest rate on money; the central bank charges you $5 per year for every $100 you have in your pocket (or in your account at the central bank).
3. Let's put 1 and 2 together. "Positive interest helicopter money" is when the central bank prints new money to pay you interest on the money in your pocket. "Negative interest vacuum-cleaner money" is when you pay the central bank interest on the money in your pocket and the central bank burns it.