Default Controls:
U on keyboard/(Hold A) + Down on dpad for normal ragdoll
I on keyboard/(Hold A) + Up on dpad for stagger/drunk ragdoll 
(Use movement keys/controls to move drunk ragdoll)
When ragdolled press the same thing again to go back to normal.
Note: You can change controls with config.ini
Installation: Download Alexander Blade's Scripthook here: http://www.dev-c.com/rdr2/scripthookrdr2/ if you haven't already
Then place "Simple ragdoll.asi" and "config.ini" in your RDR2 directory (Mine is: C:\Program Files\Rockstar Games\Red Dead Redemption 2).