get back up(redirected from get their backs up)
get (one's) back up
To become or cause to become angry, hostile, defensive, or irritable. John got his back up when his parents brought up the subject of college. Election season always gets my dad's back up.
get back up
To return to an upright or standing position, especially after having fallen or after having sat or lain down. I know you just sat down, but I'm afraid I'm going to have to ask you to get back up—those are not your seats. He's taken a beating tonight, and this might be it for the champ. No, wait, he's getting back up!