Assuming one is not allowed to invest the money in any sort of security, asset, real estate, business, plant and equipment, or anything else for the purpose of generating a return, then the best answer is super-high-end vacations with super-high-end hookers and mountains of blow. Anyone who says otherwise is a prude or a doofus or both. What if you took four or five of your best friends out, once a month, to some ridiculous corner of the world for an absurdly extravagant, hell-raising weekend? I imagine you'd be pretty fucking popular when the year was over.