I just don't get it. What purpose do these signs serve? I totally understand why you might wear a baby on board badge on the tube, that has a purpose. But why a car sign? Are other drivers supposed to be behave differently around you "more safely" or perhaps just be forewarned that you may have poor driving or parking as you may be sleep deprived. Aibu to find this pointless signalling irritating? Maybe someone with one of these signs share why?