Pay close attention around 0:16 mark. Selena is listing reasons that she should've dumped her ex-boyfriend (How appropriate!) and of them includes the fact that his "ringtone was 'N--ga What, N--ga Who.'"
You really have to listen up, because Selena's voice suddenly drops in plain recognition of the fact that she really shouldn't be saying a line like that.
Sure, she's playing a character and the line is a reference to a 1999 Jay Z song, but still makes for an odd dialogue choice that's more likely to confuse audiences than elicit laughter.
For one thing, that song came out when Selena was six years old. Surely, the screenwriters could've chosen a more age appropriate hit for her to name drop.
Secondly, the more popular radio version of the track was titled "Jigga What, Jigga Who." Couldn't Selena have just said that?
Particularly in the wake of the Justin Bieber's racist video scandal, it seems the producers of Behaving Badly decided to include the scene in their final cut in order to desperately drum up some publicity for a movie that's destined for the bargain bin at Wal-Mart and a handful of Razzie Awards.
Unfortunately, they used Selena as their unwitting pawn.