Sign up and put in credit card (maybe use stripe) or paypal info, choose which course you're taking (on coursera, udacity, etc.), and set an amount you want to "wager" on finishing that course (and a date to finish it by if it's a pace yourself course). Come back when the course is over and upload your certificate to prove you finished the course before the deadline (with email reminders). Make money for finishing it (paid for by people who didn't finish).