The term "mice and men" stems in all likelihood from a poem by Scottish poet Robert Burns. The poem, written in written in 1785 and dubbed "To A Mouse, On Turning Her Up In Her Nest With The Plough" contains the passage:

"But, Mousie, thou art no thy lane,
In proving foresight may be vain;
The best-laid schemes o' mice an'men
Gang aft agley,
An'lea'e us nought but grief an' pain,
For promis'd joy!"

For those of you with a less than celtic background, just read the passage through aloud without focusing too much on the individual words.