I too have seen people wear their bibs over their jersey. I too don't understand the reasoning behind it. I have also seen people tuck their jersey into regular riding shorts as well. I'm not a slave to fashion but the dorkness factour in both practices well overfloweth my cup. I mean, we already look fairly dorky just being in cycling gear. The only thing worse I've seen was in the movie Big Trouble in Little China when Kurt Russell was walking around with his shirt poking out his unzipped fly.