Used to describe a particularly daunting and tedious task, but usually one with very good outcomes. Originates as a reference to the programming of the first computer, the ENIAC (Electronic Numerical Integrator And Computer), which would take hours to program simple math functions. Programming was done with a series of switches and in binary (1s and 0s).
"Passing Ms. Smith's English class is like programming the ENIAC."
by Frank The Box Monster November 12, 2013