I heard a country-western song in which a pool hustler got out-hustled. In the song, the super-hustler says "I only play off the wall with friends", then goes out to his car to get his custom-made pool cue. I assume "off the wall" means the cues on the rack in the pool hall, and thus "ordinary" or "common-place".

Do you all use that term that way? Most peope use "off the wall" to mean "wild and crazy", as in "off the wall idea", with suggestions the thinker is bouncing off the walls.

I don't play. I was just curious. Terms sometimes get changed outside of their sport. For example, I know that "up to par" means "average" to most non-golfers, but "par" is darn good. If you could shoot par consistently, on championship courses, you'd be somewhere between 10th and 40th place in the PGA tour. Not #1, but you could make a comfortable living working outdoors in pleasant surroundings without having to wear a tie.