Those of us out here using corporeal punishment, and living with grumpy children forced to tow the line, grow weary of our unpopularity.
I always thought that it was "toe the line."
It is. It's a term from prizefighting (boxing), specifically the he London Prize Ring rules which had been accepted in both Britain and America in 1838.
These rules, which were first used in a championship fight in 1839 in which James “Deaf” Burke lost the English title to William Thompson (“Bendigo”), provided for a ring 24 feet (7.32 metres) square and bounded by two ropes. When a fighter went down, the round ended and he was helped to his corner. The next round would begin 30 seconds later, with each boxer required to reach, unaided, a mark [it was a line] in the centre of the ring. If a fighter could not reach that mark [could not "toe the line"] by the end of eight additional seconds, he was declared the loser. Kicking, gouging, butting with the head, biting, and low blows were all declared fouls. (Source:Birmingham Fight Club)The length of the rounds were not fixed; a round lasted until one of the fighter's was knocked out of the ring, or his knee or hand touched the canvas. The number of rounds wasn't fixed either, which is why there are recorded fights like: "In 1889 John L. Sullivan beat Jake Kilrain in 75 rounds to defend his heavyweight championship"(same source).