Selena Gomez's Sneaky Revenge

Selena Gomez showed her feisty side at her UNICEF concert on Saturday night with a trio of carefully chosen boy trouble songs -- Taylor Swift's "I Knew You Were Trouble," Justin Timberlake's "Cry Me A River," and Britney Spears' "... Baby One More Time" -- but J-14 Magazine has exclusive video of how she ended her "revenge" songs with a sly little giggle, possibly showing just how satisfying it was to sing those specific songs at her first stage show in more than a year -- and one of her first public appearances post-breakup from Justin Bieber.

Selena also went out of her way to avoid even saying the word "Justin" by introducing Timberlake's song as "*NSYNC's J.T."

For more details and J-14's exclusive video of Selena's giggles, visit J14.com.