A day for motorists to pose as cyclists for one day so that they can brag to their workmates about how healthy and environmentally conscious they are.
Bill: "I biked to work on Bike to Work Day. It's great to know that I'm keeping fit and saving the planet."
Jeff: "Bike to Work Day was three months ago. Have you biked to work since?"
Bill: "No way! The road is too scary. Once a year is more than enough."