At Waltham (thankfully a yellow jacket free zone, usually) the other day, a bunch of people arrived in some nondescript aircraft, got out in their yellow jackets, and then stood around wearing them in the Bar. Were they worried that someone might taxi into them and spill their drinks? I suspect that they were in some way trying to differentiate themselves from the plebs: "look at us, we're FLIGHT CREW". Whether these were the same people callking the a/g for takeoff clearances etc later on I know not, but I have my suspicions.