The best replacement for crazy is insane.

The best alternatives to crazy are rated as following:
★★★★★  insane
★★★★  genius
★★  hot
★★  psicosis
★★  stupid
★  psychic
★  game stop
★  psycho
★  eccentric
★  tajiri
★  hot himym
  mad
  mentally ill
  fluenz
  crazy
  sane
  new frontier lower
  check it out

Your alternative for crazy is not listed? Suggest!
Speaking about crazy, one probably shouldn't forget about twins.

Other search terms related to crazy and their ratings are:
★★★★★ twins
★ this razor with this razor im crazy
You have in mind a companion for crazy and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of crazy in all years. Click on graph for more.
crazy
insane
genius