from Engineering Unit Conversions, 4th Ed., M. Lindeburg, P.E.
diagram: two monograms
dogleg severity: an actual indication of pipeline kinkiness, as measured in angular degrees of deviation from straight per-unit length
duckland utilization hours: a measure of the amount of time a duck might sit in a wetlands area. Actually used in migration studies.
Eskimo pi: ratio of an igloo's circumference to its diameter
helen: a measure of female beauty
millihelen: the amount of beauty needed to launch one ship
lpf: litres per flush
microscope: one millionth of a mouthwash
senator: one hundredth of no decision
won ton: 2000 pounds of Chinese soup
word: one millipicture (since one picture = 1000 words)
yea or yea: about 2.5 feet (as in "about yea long")