In the movie, this was given to Scott by Ramona after their first unofficial date so that he could call her back. It had 7 x's written along with it. Scott thought it just meant kisses until Wallace points out that it actually means she has 7 evil exes. According to some of the commentary for the film it is a New York number but they are unsure what it is for.
7 little kisses?..........7 DEADLY EXES!