Deucimetry
The process of measuring various parameters of a toilet bowl (e.g. circumference, perimeter, volume) relative to the size of one's excrement. Units of measurement are usually reported in 'logs', 'picoturds', or 'kilosnakes'.
The morning after a large meal, John was able to perform deucimetry to determine the volume of his home toilet: 3.22 kilosnakes.