I'm sitting at a coffee shop and eavesdropping (obviously) on some sort of business conversation between a man and a woman. In regard to something that I didn't hear, the man uses this analogy to emphasize the impossibility of whatever it is he is talking about:
It's like riding a unicycle. It just does not work. You need two wheels to get going.
He does know people ride unicycles, right? I so hope this lady he's talking to can ride a unicycle.