My MP3 player
Household appliances (washer, dryer, etc)
My car ($self->park(), anyone?)
My family and/or relatives
Anything on Gizmodo
Results (392 votes), past polls
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 (129 votes),