"Aren't you supposed to be in rehab now?" Letterman asked the "Scary Movie 5" star, whose laughter came to an immediate halt as soon as she comprehended the inquiry.
"Do you not watch anything that goes on," Lohan responded. "What are you, a tabloid now?"
She reluctantly satisfies Letterman's curiosity by explaining that on May 2 she'll begin a three-month treatment in a rehabilitation clinic — a similiar facility to which she has checked into "several" times before.
"How will this time be different? What are they rehabbing, first of all? What is on their list?What are they going to work on when you walk through the door," asked Letterman.
"We didn't discuss this in the pre-interview," a visibly uncomfortable Lohan asked.
The interview gets more awkward when Letterman asks if she has "addiction problems."
Watch Lohan's ice-cold stare and the, uh, zinger that follows in the video below: