Old Joke Is Good Joke

It's from The Town and Country Almanac, 1799 (found at Futility Closet):

A scholar, a bald man, and a barber, traveling together, agreed each to watch four hours at night, in turn, for the sake of security. The barber’s lot came first, who shaved the scholar’s head when asleep, then waked him when his turn came. The scholar scratching his head, and feeling it bald, exclaimed, ‘You wretch of a barber, you have waked the bald man instead of me!’