Bieber, getting the business from Letterman. (John Paul Filo/AP)

Justin Bieber has been coddled on talk shows for too long. Last night, David Letterman finally put a stop to that.

During an appearance on “The Late Show,” Letterman became the equivalent of the Biebs’s stern father (or perhaps, as Bieber put it, “grampa”), telling the 18-year-old he worries about him, insisting he should become a U.S. citizen so he can vote in this country and encouraging him to go to college.

Then Letterman got really hard-core and tried to erase a recently acquired tattoo from the tween heartthrob’s arm. Weirdly, the word “Believe,” the name of the new CD etched on Bieber’s pop-star skin, appeared to slightly fade as a result.

During a musical performance, Bieber tried to explain why that happened: “Turns out it was just one of those lick-on ones,” he said.

The interview only got more awkward after the tattoo incident, as Bieber revealed that he apparently thinks the Sistine Chapel is the “Sixteenth Chapel” (“Canadian high school,” Letterman quipped), made it clear that he really isn’t sure what his fragrance Girlfriend smells like (“really, really good” was the best he could come up with) and also appeared to have only a vague grasp of where his world tour will take him this summer.

Thanks, Letterman. Now I’m a little worried about Bieber. As for the talk show host, he apologized to Selena Gomez’s boyfriend for being “too snappish” with him. Watch the clips below, as they may mark the last time Bieber ever appears on “The Late Show with David Letterman.”