Sunday, after Lady Gaga’s live first-ever YouTube Music Awards, where was she?

With me.

I’m back from Ischia. Car to a boat, boat to a car, car to Naples airport, bus to a plane, bus off the plane in Rome, flight to New York and, after five days in Italy, car to Italian restaurant Joanne Trattoria. Owned by Gaga’s parents.

Her father announced: “Steffi’s coming over.” From a black SUV in comes Steffi a k a Gaga. Like any local 20ish kid. Plain long hanging brown hair. Boyish Cap. No makeup. No jewelry. Dark glasses. Giant clunky black patent 8-inch heels. Gray overshirt. Underneath, no long pants.

So after going naked in London, maybe not even short pants? “Listen, that was because it was a gay club,” she said.

This was dinner with Barbara Walters, dressed like for the Oscars, and Joan Rivers in red chinchilla. After a 21-hour trip, I was a poster for “Send This Child to Camp.” So tired that my head was in the meatballs, I don’t remember what Gaga said. I think she said she’s writing a book. We took pictures. Then she hung at the bar with her gang “and my boyfriend Taylor Kinney of ‘Chicago Fire.’ ”

She then picked up our check. At that point, my head came out of the meatballs.

What happens in ‘Vegas’?

About the newie movie “Last Vegas”:

Morgan Freeman: “I’m shooting ‘Life Itself,’ another film, here where Diane Keaton and I play an old couple whose niece wants us to sell our Brooklyn apartment. Fortunately, I don’t worry about being forced to sell mine because I have none. I’m at the Mandarin Oriental.”

Mary Steenburgen: “I’ve written music seven years but never talked about it. I play piano and accordion. A song I wrote is in this movie. So many stars coming up, producers only get around to me now and then so you must keep going.”

Walking past: Dick Cavett and new(ish) wife. Regis Philbin and new gray hair. Jane Rosenthal and new sequined coat. Rosanna Scotto’s date? Her son. Les Moonves’ date? His daughter. Ashleigh Banfield’s date? “Aaron Sorkin. He needed a ticket, so I helped him out.”

Michael Douglas: “I’m in all these great movies, and somehow I’m remembering my first shot at it. Like my first screen test. God, I was terrible.”

Robert De Niro. Sequestered. Alone with the beautiful wife, who said where she bought her newly long hair. I schlepped up steep stairs to a private isolated Green Room. His Charmingness greeted me with: “My favorite gossip columnist!” Hugged me, kissed me, smiled at me. Said nothing. Then: “My first audition was, I think, ‘The Wedding Party.’ Or ‘Godfather.’ No, maybe with Brian De Palma. I was in my 20s. Listen, who cares? Say what you want? Make it up.”

Afterthought

Today schools sure are tough. In fact, someone just told me that one 8-year-old kid on the debating team was recently busted for using steroids.

Odds & ends

Might a famous TV chef be sniffing more than casseroles? . . . Kerry Washington wore Rubin Singer’s gown on Thursday’s “Scandal” . . . Flipeez sponsored a party at Bklyn Beast with Swizz Beatz, Knicks’ Carmelo Anthony, designer Rebecca Minkoff and DJ Fulano, age 10 . . . Tomorrow “Moschino loves Disaronno” launches its holiday liqueur $24.99 bottle designed by fashionista Moschino . . . Lawyer William Zabel’s David Kassan portrait was to hang in P.J. Clarke’s. But it lacked a frame. No problem. Some savvy attorney heisted one from another wall painting . . . Retired baseball star Jim Palmer, eyeing fotogs snapping his wife’s Palm Beach decorating shop: “Previously, I was the one everybody snapped pictures of.”

Woman wearing Chanel suit, Hermès bag, Roger Vivier shoes, Loro Piana scarf asks the doctor in his office: “How come you don’t take my medical insurance?”

Only in New York, kids, only in New York.