The development of larger aircraft and advances in design have reduced the occurrence of air sickness. This has led to bags being given a secondary use as general purpose waterproof waste containers which is often reflected in the labeling of the bag and instructional diagrams. Another common use is that of a photographic mailing envelope (especially Australia). Airlines have also printed bags to serve as card game scoresheets and Continental Airlines once suggested that they be used as doggy bags for airline food. Non-airline aircrew have occasionally used these bags as improvised urinals or fecal collection devices aboard aircraft lacking on-board toilets. A specialized urine collection bag known colloquially as the "piddle pack" developed as an improvement from this practice. In 2010, Spirit Airlines began selling advertising space on its air sickness bags.