Angua hefted Carrot's new boots. They were the size of ox-carts.
"You know what they say about guys with big feet," she primed.
"No. What?" said Carrot in the most painfully naïve way Angua could imagine.
"Er... They wear big shoes."
"Oh." Later on Carrot made his way to the watch-house where Commander Vimes sat behind his desk…
His face lit up when he saw Carrot's new boots. "Is it true what they say?"
"In my experience it is."
Vimes's mouth dropped open. Carrot had just told a dirty joke. Vimes leaped under his desk and waited... for the apocalypse.