Reunited: Justin Timberlake and Cameron Diaz

Shrek The Third - UK Film Premiere

For a Movie! Why would exes choose to be in a movie together is beyond me but whatever!

He has signed on to star alongside her in the comedy The Bad Teacher.

According to Variety, Diaz, 37, plays a middle school teacher who gets dumped by her boyfriend.

She begins crushing on another teacher, played by Timberlake, 29, who happens to be dating a fellow teacher, played by actress Lucy Punch.

I guess these two are friends now, they did break up like 3 years ago…but how does Jessica Biel feel about this?