Stephen Colbert  made an appearance on The Late Show With David Letterman on Tuesday, joking with Letterman about his upcoming late-night takeover. Earlier this month, it was announced that Colbert will replace Letterman  when he retires in 2015, signing a five-year deal with CBS to host the show. After the news broke, Colbert — as his alter ego — joked on The Colbert Report that he "doesn't envy" Letterman's replacement , but he stepped out of character on Tuesday, telling Letterman that's he's "thrilled" about the opportunity. Letterman joked, "They could have just as easily hired another boob like me, but they didn't," and Colbert added, "Every boob is like a snowflake, Dave. We're all unique in our own way." Watch their funny interaction above.