If she is not a drug user -- she tells Morgan she smoked "some pot" a year ago -- or an alcoholic, then why would she need rehab, Morgan asked.
"This is where it gets hard for me to explain," she said. "I don't think there's anything wrong with people taking time to just be by themselves. I think people want to see me do that. They will keep saying the same things about me if I don't. I don't think it will be a bad thing for me to be away with myself for three months."
Although now confessing to Morgan that she used drugs a year ago, she told Matt Lauer on NBC's "Today" show a year ago that that she was "clean and sober" then for "a long time."
Although she was once arrested for cocaine possession and later sent to rehab when she violated probation by testing positive for the drug, Lohan said she rarely used it since "I don't like it."
Cocaine: Not her favorite drug
"It reminds me of my dad," she said. "I took it four times in a period from about the age of 20 to 23, and I got caught twice."
Cocaine made her feel "a little too buzzed -- it made me feel uncomfortable," she told Morgan.
She's not "a junkie," she said. "It's the truth. I've never taken heroin either, never injected myself with anything, never done LSD. Those things all scare me."
Her drugs of choice are "pot, obviously, and Ecstasy," she said. "I liked that (Ecstasy) better than the others." Morgan reports Lohan then giggled.
Lohan: Not a junkie
Lohan has previously acknowledged having a drug problem, though. She posted this Twitter message in September 2010 just before entering the Betty Ford Clinic for three months: "Substance abuse is a disease, which unfortunately doesn't go away over night. I am working hard to overcome it and am taking positive steps."
Lohan claimed to Morgan that she's just misunderstood. The constant online tabloid reports of late-night partying, which sometimes results in legal issues, don't show the real person.
"I've never been a junkie, and never will be," she said. "I just like going out late to clubs with friends and listening to music. Always have done. It's not that unusual for girls of 26!"
Heath Ledger's advice
She slowed down on her drinking on the advice of an actor, Lohan said.
"Heath Ledger told me to give it up for a year because he'd just done that, and so I did, and it wasn't a problem for me," she said. Ledger was 28 when he died from a prescription drug overdose in January 2008, a year after Lohan's first rehab visit.
Lindsay prefers men
Lohan also talked to Morgan about her sexuality -- she's straight despite a past relationship with a woman. "I like boys," she said.
"I know I'm straight," she said. "I have made out with girls before, and I had a relationship with a girl. But I think I needed to experience that and I think I was looking for something different."
She said she was in love with Samantha Ronson during their relationship, and "I still love her as a person."