This document discusses a laboratory exercise where students rated the intensity and offensiveness of various mystery liquids on a scale of 0-6. The liquids tested included tap water, cologne, raw swine wastewater, facultative lagoon wastewater, covered anaerobic lagoon wastewater, and aerobic lagoon wastewater. Graphs show the results of these smell tests from 2003-2010, with raw swine wastewater generally rated as most intense and offensive while cologne and tap water were mild. The goal is to have students discuss smells in a scientific manner.