I tried to answer a stranger's question about my job and accidentally taught a whole coffee shop wrong info
Last Tuesday I was waiting for my order at a cafe in Boise when a guy at the next table asked me to settle a bet about how long a piano tuner takes to tune a piano, because he recognized me from the shop where I work. I told him 45 minutes, which is the number my old boss drilled into me years ago, and the whole table nodded like that made sense. Two minutes later a real piano tech walked in and heard us, and he very politely explained that most tunings run 75 to 90 minutes plus a follow up visit, and mine was just the shop's flat rate slot for a quick touch up. So now I am the guy who confidently spread bad info to five strangers in a coffee shop, and I want to know what common 'facts' you have repeated for years that turned out to be flat wrong.