Bisexuality and Bicycles

Listen here, you dimwit. You, John Grimm, are clearly not very bright since you wrote this brain-dead joke. Let me break it down for you. People often deny the existence of bisexual men. This joke plays on that denial by saying it does not exist 'because it doesn't cycle'. 'Cycle' here is referring to the 'bi-cycle' or bicycle. Get it? It's wordplay and a reference to the stereotype that bisexuals don't exist.