This can either be used to make a silent synchronised dance party that confuses the hell out of all non-sync'd people in the immediate vicinity, or allows those involved in the sync to enjoy songs simultaneously, without the need for big audio equipment or the disturbance of others.
Perfect timing for starting respective albums/playlists is essential and requires much practice.
Jim: Sure, how about we sync that legit playlist I made last week?
Lucas: Ok cool.
Angus: Hold up! Let me get in on that shit too!
1...2...3... *All press play*