But my train is on yo track now
So watch out
He is metaphorically saying he is having sex with your girl! The “train” imagery has been used many times before, notably in Hitchcock’s famous movie North By Northwest (1959).
You can see the brief, final scene HERE
To help improve the meaning of these lyrics, visit “Body Count” by Justin Timberlake (Ft. Timbaland) Lyrics and leave a comment on the lyrics box