Radar (song)

"Radar" is a song performed by the pop music singer Britney Spears. 
It was originally supposed to be the fourth single released off of her fifth studio album "Blackout". 
It ultimately wasn't but despite that fact it did chart in some countries. 
It was later included as a bonus track on her sixth studio album "Circus". 
It was released as the fourth single off of that album.