By DAVID BAUDER
AP Television Writer

NEW YORK (AP) ó One night after his memorably weird interview with actor Joaquin Phoenix, David Letterman made a joke in his “Late Show” monologue questioning whether Phoenix was on drugs.

The actor had appeared to forget the name of his “Two Lovers” co-star, Gwyneth Paltrow, stuck gum under the edge of Letterman’s desk and apparently cursed at bandleader Paul Shaffer for laughing at him during Wednesday night’s show. The appearance put Phoenix up with Farrah Fawcett on the list of late-night TV guests memorable for the wrong reasons.

Letterman on Thursday said that since so many of today’s stars appear screwed up on one substance or another, “we’ve put together the ‘Late Show’ celebrity drug update.”

Video of Olympics swimmer Michael Phelps appeared with the caption, “Michael Phelps: Weed.” Baseball star Alex Rodriguez followed, captioned “Alex Rodriguez: ‘Roids.”

Then came a picture of Phoenix from the night before, wearing sunglasses and a long, black beard and the caption: “Joaquin Phoenix: ???????”

Phoenix’s older brother, actor River Phoenix, died of a drug overdose outside a Los Angeles nightclub in 1993.

Hours after Joaquin Phoenix’s Letterman appearance, which was punctuated by intervals of uncomfortable silence from both, it became an Internet sensation. By Thursday evening, it had been viewed more than 180,000 times on YouTube.

“I’m sorry you couldn’t be here tonight,” Letterman said at the interview’s end.

Phoenix, a two-time Academy Award nominee, announced last October that he was quitting acting to concentrate on a career as a hip-hop musician. He has said that “Two Lovers,” a romantic drama, is his last movie. It’s such an odd career switch that some are wondering if it’s all an act, particularly since Casey Affleck was following Phoenix with a camera to film him at the “Late Show.” Phoenix has insisted it isn’t.

Letterman drew immediate attention to Phoenix’s appearance when the actor sat down for his interview.

“I will just say right off the top here, you look different than I remember you,” the talk show host said. When he asked, “How is the beard?” and the audience laughed, Phoenix mumbled something about being made to feel weird about his appearance.

Phoenix appeared on the show to promote his movie. Letterman asked about Paltrow and momentarily forgot her name. Phoenix couldn’t, or wouldn’t, help him. Following a few seconds of uncomfortable silence, Letterman said, “Can you tell us about your days with the Unabomber?” Phoenix didn’t reply, but allowed the slightest hint of a smile at the joke.

They talked about Phoenix’s decision to quit acting. When Letterman asked why, Phoenix replied, “I don’t know.”

“Here’s my hope, after a little time off ó and I think you’re taking a little time off tonight ó I’m hopeful you will reconsider and come back to acting because there’s nobody really better than you are,” Letterman said.

Letterman veered between mocking Phoenix and trying with little success to draw something out of him. When Letterman asked if Phoenix had fun working with Isabella Rossellini, he said, “Yes,” but was silent when questioned whether he had any stories to tell. “I’m sure something fun happened,” Phoenix said.

Phoenix’s desire to be a hip-hop musician was met with little enthusiasm from Letterman. “I’d love to come on the show and perform,” Phoenix said.

“You know, that seems unlikely,” Letterman said. “We’ll certainly keep you in our Rolodex.” The audience laughed and Phoenix said nothing.

Letterman asked Phoenix to introduce a clip from “Two Lovers,” which seemed so unlikely given how the interview was going that Shaffer guffawed.

Phoenix turned to Shaffer, asking “are you … serious?” with a word bleeped out. He wondered aloud why the audience was laughing at him. “What do you have them on? Is this nitrous?” Phoenix said.

And when Letterman noted that the actor was chewing gum during his interview, Phoenix took the wad from his mouth and stuck it under the lip of Letterman’s desk.

The general weirdness made viewers ó and Letterman ó recall Farrah Fawcett’s memorably spacey “Late Show” appearance in 1997. “We owe an apology to Farrah Fawcett,” Letterman said at the interview’s end. In Fawcett’s appearance, the giggly, distracted actress talked about using her body parts to paint pictures and briefly thought Letterman’s stage backdrop of a New York City skyline was real.

A spokeswoman for Phoenix did not return a call for comment on Thursday.

The 34-year-old star received Oscar nominations for his roles in “Gladiator” and “Walk the Line,” for which he learned to play guitar to channel country legend Johnny Cash.

Phoenix, in a recent interview with The Associated Press, said that he grew his beard as a way of distancing himself musically with his best-known acting role, Johnny Cash. He acknowledged that his career change looked odd but said he is utterly serious about it.

“I have better things to do than just, like, (mess) around with people,” he said. “This is my life and this is my work, and this is the thing that I’ve been passionate about. Just because it’s hard for other people to recognize and to see that, look, I get it, dude. I know that it seems … weird. … But I can’t let that affect my life and the things that I want to do.”