Erg

An erg is a unit of measurement or energy or work that is the same as 10-7 joules. It formed part of the centimetre-gram-second system of units (CGS system of measurement which is no longer used). 
An erg is about the amount of work done (or energy consumed) by one common housefly performing a "press-up", the leg-bending dip that brings its mouth to the surface on which it stands and back up.