Improbable Research announced the winners of its 2011 Ig Nobel Prizes during its 21st annual prize ceremony this week. The prizes are meant to celebrate the most unusual kinds of science and research that "first make people laugh then make them think," the organization says. This year, the Ig Nobel in medicine was awarded jointly to a team of researchers from Belgium, the Netherlands, and the UK, and to a team of investigators from Australia and the US, for demonstrating the types of decisions people make "when they have a strong urge to urinate." The prize in biology went to researchers from Australia, Canada, and the UK, who showed that males of a particular species of beetle can mistake a certain Australian beer bottle for their female counterparts, enough so that they try to mate with it. The chemistry prize went to a team of Japanese researchers for "determining the ideal density of airborne wasabi (pungent horseradish) to awaken sleeping people in case of a fire or other emergency, and for applying this knowledge to invent the wasabi alarm," Improbable Research says. The organization awarded its mathematics prize to the myriad people who have, over the years, 'calculated' the dates and times the world might end, "for teaching the world to be careful when making mathematical assumptions and calculations," it says.