When I was at university, posters appeared everywhere saying that on the following Thursday (they didn't quote the date) the medical faculty was prepared to pay one pound (a lot of money for an impoverished student in the sixties) per person for urine samples which they required for a research project. A note at the bottom requested that people brought the specimen with them. There was a queue of students right around the block each with a bottle clutched in their hand. Containers had been filched from anywhere - there were no empty milk bottles on doorsteps for miles around. After the joke was exposed, the bottles of "amber fluid" were left all standing along the length of the Medical Faculty wall.