Texting during the movie, e.g

• Words for Nanette
• Thing you shouldn't do
• Proscribed activity
• Off limits
• Putting regular gas in a diesel engine, e.g
• Something banned
• It's out of bounds
• Taboo to a toddler
• It's strictly taboo

Wiktionary Word definitions in Wiktionary
n. (alternative spelling of no-no English)