Swearing
From Tardis Wiki, the free Doctor Who reference
Swearing was the use of speech considered rude.
The Malmooth Chantho respectively began and ended her sentences with "chan" and "tho"; as she explained to Martha Jones, to not do so would be akin to swearing. (TV: Utopia)
Yasmin Kahn's grandfather often swore loudly in Punjabi when he accidentally injured himself. He hoped that his young granddaughter hadn't understood, but she had. (AUDIO: Fallout)