From my paycheck, my wife and I each get $100 per month "allowance" that we can spend on anything, no questions asked, and unused amounts stay in the bank for future use. We also put aside $50 for "family fun" (movies, restaurant trip, etc.). My SAH wife does side jobs occasionally, and we use a small percentage of those proceeds to add to the budget for those three categories, with the majority of her income going to long term goals that roughly match how my paycheck is allocated. We have a budgeted amount for vacations, clothes, subscriptions, etc., so this is just for pure "play" reasons.
I come from a fairly conservative financial background and have been a pretty strict budgeter for most of my adult life, but allowing ourselves to potentially spend $100 / month on whatever the heck we want is a mental thing for us. First, if my wife and I disagree about some purchase that one of us thinks should come out of one of our "normal" budget categories, that person can use their personal funds to just get it if they feel that strongly about it. Second, we have a guilt-free way of doing spontaneous stuff like grabbing Starbucks while out running errands, buying the kids a small treat when they do something to earn it, or buying a round of drinks for coworkers. In general, I usually end up spending around all of mine every month, while my wife saves up most of hers for 3 or 4 bigger purchases per year. It works for us, YMMV.