BECAUSE WE MAKE LITTLE BAGELS!!!
But here's the real story:
When The Chief was serving his mission in Argentina for the LDS Church, his companions and mission buddies dubbed him "Bagel" for its similar sound to his true last name. It stuck. We married. Buddha Bagel, our first miniature (a clone of his daddy), came along shortly thereafter and the tradition has continued so on and so forth with Bagel Baby #3 due in just a few short weeks here.
Were you hoping for some long, deep explanation?