Upton's cover shot for Sports Illustrated was unveiled Monday on a billboard across from the Ed Sullivan Theater by "The Late Show with David Letterman."
Upton and nine other models from the issue also stopped by Letterman's late night show to help him deliver his top 10 list, which focused on why this year's Swimsuit Issue is the best ever.
One cryptic reason was that the magazine apparently includes ten models, but only nine swimsuits, while another was, "It's not in 3-D, but it looks like it is."
Cover star Upton offered this enticing reason: "The art department was able to airbrush my mustache."
Clearly this is a woman with a sense of humor, and we'll likely get to see more of it when the 19-year-old returns to "Late Show with David Letterman" Tuesday night for an interview.
Upton, who had a role in 2011's "Tower Heist," will also appear in the Farrelly brothers' "Three Stooges" in April.
