We, at JoyTunes, ran hundreds of ab tests in the past three years. Some are simple (red/green buttons), some are complex (full pledge features that took weeks to implement). Over the years we developed some intuition on our users - what is likely to work and what is not. But every once in a while came a test that just blew our minds - tests results that were so surprising that no one expected them. In this talk I will share a few of those ab tests and their unexpected results.