I invented a dry-erase board that folds up to pocket size. Originally it was for hitchhiking: I was getting discharged from the Marines in California and thought it would be neat to hitchhike back home to Ohio, so I'd need a sign, but cardboard's single-use and whiteboards are big and bulky. There was lots of packing tape and index cards around and I just put them together! You can see it here on Amazon if you're interested.
Hah, I didn't sell the business explicitly to become a mascot. The businessy part of business — hiring people, making connections, squeezing dollars — isn't really my thing. I'm a little phone-shy and agoraphobic, and so figured the business was better off in someone else's hands.
After selling it I moved in with my girlfriend on the other side of DC and started looking around for ways to get to know the community a bit. Back in the Americorps I spent a day dressed as a giant chicken for a fundraiser and had a BLAST, and so kept an eye out for other mascot opportunities. This baseball team had a posting up on Craigslist so I went for it!
It doesn't pay the bills by any means, but being a mascot is just plain fun. When you're dressed as a giant dog you can act however you want, be however you want... You can spend an evening stealing people's hats and pretending to run off with their food and everyone just thinks it's funny! And it's so much fun running around with the kids.
Plus, doing lots of musical theater in high school left me really only knowing how to dance in a theater-y way. That's not great for parties, but it's great for mascoting!