(I work in a photography store. We also take passport pictures. We have two chairs: one for adults, one small Tripp-Trapp highchair for kids. This happens when a man walks in and wants a photo taken.)
M = me
C = customer
M: I’ll take the photo over there, please sit down to the BLACK chair.
C: Ok. *sits down to babies’ WHITE Tripp-Trapp*
M: Sir, that chair is for babies.. Could you please move to the black chair?
(At this point customer turns red, manages somehow to get up from the baby-chair and storms out from the store clearly embarrassed. I can tell you, when 150kg/200cm man sits in a baby chair, it looks very hilarious! And this happens A LOT.)