1. To become romantically involved with someone else's significant other, especially when done by a man. I can't believe that guy bird-dogged me and stole my girlfriend!
2. To pay close, usually unwelcome, attention to someone else. Would you quit bird-dogging me and let me work in peace?
bird-dog
1. tv. to take away another man’s girlfriend. Why’d you have to go and bird-dog me, your best buddy?
2. tv. to supervise someone; to tail someone. Marlowe knew somebody was bird-dogging him, but he was too smart to show it.