perldoc perlfaq1 | perl -ne '/((?<=")(.+hack...(?:OR)?))/&&die$2.$/' -
See also One-liner japh, Just Another JAPH, Opere Citato Japh, and JAPF for the same idea (some of these only work with older versions of perl though).
By rote learning.
Via Genetic memory.
It's provided by my firmware.
I just remember them.
Thirty days hath September
My computer gets it right, usually.
I just ask someone else.
Someone punches me on the first of the month.
Results (151 votes),