Way back when I was instructing. I was teaching a guy on a trial lesson, he was having fun and neither of us noticed his girlfriend in the back seat starting to wretch. When I did eventually recognise the unmistakable waft of smell in the cabin i looked round to find she was being sick into something, oh no not a sickbag...but one of those cardboard funnels you use to fill up the oil !! The vomit was making a neat squirly pile like a mister whippy ice cream as it dribbled through the hole in the bottom of the funnel, all over my yellow tabbard on the floor !!!! Did make me laugh(much later on).