TMZ spies caught Justin's ex enjoying a night of drinking and partying with former *NSYNCer JC Chasez -- yeah, Timberlake's old pal -- at club Marquee in NYC, where Spears had a very public jealous moment.
With black thong underwear sticking out of her jeans, Spears decided to check out the DJ booth. Just as she got over to the wheels of steel, the DJ pressed play on a Justin Timberlake track. By the look on her face, Britney was none too pleased.
According to our spy, Britney exchanged a few words with the DJ, and the Timberlake track was promptly replaced with something more to her liking.
Spears doesn't need to worry about the same thing happening with any of K-Fed's music.