SAN DIEGO -- Do you know what P911 means? What about NIFOC? They are online codes for "parent alert" and "naked in front of computer."

The coded language is used by kids and teens for instant and text messaging, San Diego television station KGTV reported.

Internet safety experts warn that it's complicated, cryptic and potentially dangerous.

"There are too many predators out there that could endanger their kids' lives or could sexualize them too early by sending unwanted messages and pictures and things like that and leet-speak is just a gateway to all of that," said family therapist Barbara Melton.

Leet-speek is a kind of code used by some people in which numbers often replace letters.

Melton and Susan Shankle specialize in Internet issues. They said most parents are in the dark when it comes to the new jargon.

They counseled one family whose young daughter started a steamy online affair right in front of them.

"While the mom was cooking dinner and the dad was watching television, the daughter, who was 11 years old at the time, was carrying on this conversation with this older man," Shankle said.

Even though her parents constantly checked the instant messages, the therapists said, the conversations were simply foreign to the parents.

So, how bad are the messages? Here are some examples:

• KPC: Keeping Parents Clueless
• POS: Parent Over the Shoulder
• GYPO: Get Your Pants Off
• TDTM: Talk Dirty To Me

It gets even sneakier. Some words replace letters with numbers and symbols.

Internet safety expert Al Kush recommends parents learn the language.

He said there are several online dictionaries and translators to help, such as TeenAngels.org or NetLingo.com.

"At least become familiar with it -- know it's there," Kush said.

There is software that can send you a transcript of your kids' Web chats, but if you don't know leet-speak you'll still be "k13w13$$" or clueless.

"Parental-control software is a help, but it's not a panacea. It's not the answer," Kush said.

Experts recommend placing the computer in a common area and monitoring how much time a child spends online.