I think sometimes when we are unprepared it can make things worse because we are worrying about what will happen if we do need to throw up and trying to focus on stopping it seems to make it more urgent so in that sense, carrying some plastic bags might help you to worry a bit less? Seemed to help a bit for me! Don't worry too much about other people; what can you do, hey? If you need to throw up then you need to and I think they would much rather it was in a plastic bag then anywhere else haha