Synonyms for Off-the-wall:

• adj.

  •peculiar (adjective)
  • abnormal,
  • bent,
  • way-out,
  • unusual,
  • creepy,
  • oddball,
  • wonderful.
  •quirky (adjective)
  • far out,
  • odd,
  • unorthodox.

• Other synonyms:

  •
  • surreal,
  • idiosyncratic,
  • incongruous,
  • edgy,
  • unreal.

Antonyms for Off-the-wall:

• adj.

  • irrational
    balanced, smart, stable, reasonable, wise, thoughtful, serious, sane, sound, realistic, logical, rational, well, reflective, responsible, sensible.
  • jovial
    gloomy, unfriendly, mean, unpleasant, unsociable, disagreeable, sad, unhappy, heavy-hearted, hateful, depressed, surly.
  • odd/oddball
    conventional, habitual, regular, normal, common, usual, ordinary, standard.
  • peculiar
    Familiar, abnormal, uncharacteristic.
  • Other antonyms:
    average, routine, frequent, customary, expected, garden, unremarkable, wonted, conservative, predictable, prosaic, run-of-the-mill, typical, everyday, unexceptional, workaday, commonplace, conformist.