That's only a 12" rule
That reminds me a joke...
A captain wanders into the mess one evening to find his crew all shouting and cheering while huddled round the table.
They all go quiet when the captain arrives;
"What the hell are you lot doing!? What are all these lines on the table?!" he demands to know
Sheepishly one of the crew replies "We're, erm, measuring all our willies to see who has the biggest captain"
All the crew look at their feet nervously, expecting the captain to be mad
"Ha! Well, give me that chalk and I'll show you boys what your captain's made of!"
With that, the captain takes the chalk, whips down his pants, leans against the table and draws a line.
Delighted that his line is the furthest from the edge by a small margin, he declares himself the winner.
The other sailors look sheepish again;
"Erm, we were measuring from the other side of the table captain"