The presence of a parent or an adult within earshot of a conversation that a teen is having with another teen with a topic they don't want the adults to know about.
while talking on the telephone:
Teen1:"So how was your date with the new hottie from school?"
Teen2:"Uhm...will tell you about it tomorrow..."
Teen1:"Oh! So there's parental guidance there now eh?"
The act of two lovers having sex on their parent's bed.
"we safe sex under parental guidance"