Didn't see this mentioned, but for a few years a while back I did secret shopping. I think it was 2008, I did enough shops to get about $1000 worth of restaurant food for free, plus another few hundred in actual payment.
Do it a while, and you can start to get high paying shops. There are stories of people going on cruises paid for by shopping company. Of course, it takes time to do reports, but you start to pick and choose which ones get the best bang for your buck. The best ones I did where alcohol compliance shops. I'd get $25 or so in free food and drink, and all I had to report was whether or not the bartender/waitress ID'd me. I did pappadaux/citos, TGIFridays, buffalo wild wings, a few others. But you had to be under 28 for most of them, so that went away.
Also, did one recently that was for pick up orders using phone or app for BJ's pizza. Got like $35 worth of food, and just had to take pics of the food once I got home and a few other quick questions.
While it's a longer report (2-3 hours), I did two $100+ dinner shops, one at Houston's and the other at Kona Grill. Worth it to me.
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Another idea, if you're a musician, join a band and play some shows. It's pretty good money, anywhere from $100-$300 a night. From 2007-2011, I made about $35k playing shows in a cover band, about 70-75 shows a year. It was 90% cash too. If you get into the wedding band or corporate party circuit, even better, your pay can shoot up to $500 or more a show.
