In furballs, all bets are off - I'm just trying to stay alive. I can't watch anyone elses six. But more frequently in the MA you 'll see someone chasing a target and develop tunnel vission. If I see an enemy saddling up on them, I 'll give the the ' key
If its a situation where I can't tell whats going on - I'll just call on range vox - "xxxxx- you see the spit below you?"
But all that is a courtesy - no one is supposed to be watching my 6 but me.