I’d probably go to TJ Maxx/Home Goods and go nuts. On the way home, I’d hit the liquor store, and also buy a few cartons of cigarettes. Practical AND well dressed - that’d be me.
Snort 
A DSLR camera. Costco has a Cannon kit Rebel for that right now.
Amazon. I don’t have anything specific in mind but I’d find a way to spend it all.
One Abu-Garcia revo toro STX HS baitcasting reel. Coupled with a heavy power 7’8" fast action rod {I haven’t decided on the rod yet}. The combined cost should be almost exactly $500.
.
I could buy the best camera I could for that amount. I need to replace the one I have now. The photos don’t seem as sharp as they used to be.
Or I could be practical and buy a couple of good pairs of shoes. I have really hard to fit feet and shoes for me don’t come cheap. But I would probably have enough left over for a new pair of glasses. too.
Or I could get a scroll saw and supplies to make some crafty stuff for bazaars. A work station, too, for my Dremel tool. Maybe some other stuff for it if there’s money left over.
Groceries for me! I do live by myself, but with that much money I could get some extra good stuff. I’d go for special cheeses, quality meats, and other gourmet goodies. Of course I would get stocked up on staples too. I bet I could dispose of the money in a lot less than five hours if I had to. Maybe I could take a side trip to my favorite liquor store. I actually have nothing alcoholic to drink at all in the house right now.
Based on recent events and the suggestion of many friends with far more experience, I’d buy a snow blower.
Bzzzt! Violation of OP rule #2.
I might go for a couple of bottles of really good wine. Maybe just one.
You know, when I read the OP, I thought of fishing tackle, too- maybe an Orvis Superfine fly rod with a Battenkill click-pawl reel. These would also cost about $500 on the nose.
Oooo, can I change my answer? My father got a rinky-dink electric one which is spotty at best. I want the most powerful gas-powered one I can find!
Cheat by going to the grcocery store and stocking up on lot’s of long shelf life stuff. That means 500 I don’t need to spend later that’s freed up for other things I can’t/won’t buy in the 5 hour time limit.
I do need a new laptop …so that probably gets bought in the time frame after the groceries get put away. Hey exploit the loopholes when you can. 
Assuming I can’t spend it on regular bills, I would buy a new recliner.
What kind of work shoes cost $250 for a pair?
Work shoes that you need in women’s size 8EE, which you can’t get on special or on sale.
I can stand and walk on concrete floors for 8 hours in those shoes and at the end of the day my feet DON’T hurt.
This is in contrast to some “work shoes” in the form of designer high heels I saw while working as a cobbler, which ran into the four digits.
Is paying down credit debt a valid choice?
If not, I’d be upgrading the business-type wardrobe, getting a really good hairdo/manicure, and so on, since I’m a few months from a need to job-hunt.
A Papillon puppy. Or rescue.
Ten new board games.
I had about 3 hours of drive time today and I thought to myself, “wow, my sound system is terrible.” So I’d gladly put $500 towards an amp, speakers and subwoofer. Not enough to throw in a nice new head unit, so I guess I have to dig into my own wallet a bit if I want that.
That’s the one I have. Pretty good saw, but I wish it had a larger table.
Assuming you mean true “fuck around, spend-on-me” money, and not to dance around the hypothetical with stuff like “buy $500 worth of stuff you’re going to end up buying in the future, anyway,” I might go with an electric bass. I’ve always wanted to tinker around with the bass and learn how to play it (or play it better than I play it now, and that’s only playing it from the knowledge I have of guitar.)