When Selena Gomez was on David Letterman's Late Show last night, she shared a laugh with the host over her ex-boyfriend, Justin Bieber.  

Letterman said "I remember last time you were here, you were with Justin Bieber...And that's not going on now?"  The 20-year-ld singer replied "No, I'm single. I'm so good."   The Letterman remarked "The last time he was on, he and I got into a conversation, and he said something and I said something and then he said something and then I said something, and I made him cry."

Without missing a beat, Gomez said "Well then, that makes two of us."  She got a laugh from Letterman and the audience, but did not expand on her comment.