"Hands down, man's down" means that if a boxer if fighting with his hands down, he's going to get knocked out (man's down). Some people inaccurately credit this expression to Delonte West. But anyone with ANY knowledge of rap music (not to be confused with hip hop), knows Method Man fathered the use of this saying in pop culture in 1996 on Redman's "Do What Ya Feel."
"You catch cal when you browse through my X-files,
who be next now
Man's down, hands down (i.e. hands down, man's down)
Foreground by your side when it go down..."