Brian McKnight is the hottest thing in adult entertainment -- because TMZ has learned, the singer was just asked to perform his new X-rated song at the OSCARS OF PORN ... aka the AVN awards ... and that's just the tip of the XXX iceberg.

Sources tell TMZ, AVN offered to fly McKnight out for the lavish awards gala in Vegas next January -- where he'd perform his new jam "If You're Ready to Learn," the adult-themed song that went viral on Tuesday ... containing the lyrics, "Let me show you how your p***y works."

But AVN isn't the only porn company trying to get into some McKnight action -- we're told YouPorn.com has also approached the singer, asking to license the song for its website's background music.

According to sources, several other XXX companies have reached out to McKnight as well, specifically because of the new song -- which McKnight plans to release next week on iTunes.

But McKnight isn't in a hurry to chomp at the porn bit -- telling TMZ, "I don't know what specifically I will do with this track in the future ... and I don't see myself ever performing it live, but I am flattered that people have embraced it and are having as much fun with it as I am."

There's a hilarious explanation behind Brian McKnight's new x-rated song -- the singer tells TMZ Live, he's been holed up in his house going stir-crazy with a bum ankle ... and the dirty ditty came to him in a moment of sheer boredom.

Brian called in moments ago and said, "I've been home for a month ... I've got this boot on my foot. I'm like a month away from Achilles tendon surgery, so I've been stuck in the house."

Brian added, the song "isn't for everyone. It's a parody. I'm having fun because basically I have nothing else else to do."

In case you haven't heard it ... Brian released a clip of a new song on YouTube called "If You're Ready to Learn" -- featuring the lyrics, "Let me show you how your p---y works/Since you didn't bring it to me first." 

Brian McKnight is not the father of a 14-year-old kid in Florida -- so says a DNA test -- and now, he's no longer responsible for $341,640 in back child support payments the boy's mother was hoping to collect.



As we previously reported, a woman sued McKnight last year claiming Brian is her long lost baby daddy. But McKnight didn't respond to her lawsuit, and the judge issued a default judgment against him ... which means he was on the hook for the cash.

McKnight eventually took a DNA test -- and the results showed that Brian could not be the kid's father ... so the judge promptly tossed out the case.

Brian McKnight is the proud new father of a 14-year-old boy ... so says a Florida judge.

Miriam Lee filed paternity and child support docs in Orange County, FL last year alleging McKnight is the father of her son. 

Brian never filed docs addressing her claim .. so the judge has ruled Brian's the daddy.

And now for the bad news -- the judge also decided Brian must fork over 14 years worth of child support ... which comes to a whopping $341,640.

We're told Brian's monthly support payment is $11,388 a month.

A rep for Brian McKnight tells us, "The judgment in Florida was a default judgment made without Brian present.  He's still looking to establish paternity, and is awaiting the results of a recent test."