Deanna Troy, while on Qo'nos, was admiring a Female Klingon's necklace.
"What is it made of?" she asked.
"Denebian Slime Devil's teeth," the Klingon replied.
"I suppose," Deanna said patronizingly, "that they mean as much to you as pearls do to us."
"Oh, no," The Klingon objected. "Any fool can open an oyster."
In Star Trek II: The Wrath of Khan Spock and Saavik actually speak to each other in English when they converse. The Vulcan words were created to mimic their mouth movements and dubbed in later
"Only a fool fights in a burning house."
Kank the Klingon, Star Trek (Day of the Dove)