Jiffy (physics). A jiffy, as defined by Edward R. Harrison, is the time it takes light to travel one fermi (one femtometer), which is about the size of a proton.
Smoot. The smoot is a unit of length created by a bunch of (probably drunk) MIT students in 1958. The unit is named after George Smoot, and was used to measure the lenght of the Harvard Bridge. One smoot is equal to George Smoot’s height at the time (five feet and seven inches). To measure the length of the bridge, Smoot repeatedly lay down on the bridge, allowed his fraternity brothers to mark his position, and got up again. The bridge was measured as “364.4 smoots plus or minus one ear”. The markings on the bridge are still there, as they are repainted each semester. Appropriately, George Smoot later served as Chairman of the American National Standards Institute (ANSI) and President of the International Organization for Standardization (ISO).
Got any others?