Recently, a friend of mine was going to their cousin's graduation party. My friend wanted to bring a really great cheesecake dessert, but didn't know how to make one. I taught him how to make the cheesecake from scratch in time for his cousin's party. In exchange for helping him, he taught me how to change a tire on my bike. I'm participating in a century ride in September and it would be beneficial to know how to change a tire in case I need to. This way, my friend didn't have to go buy a cake at the store and I didn't have to go to a bike shop to get my tire changed.