You will usually say damn it, but in this case you say crappit instead. Exchanging damn with crap. It really has the same meaning but has a more catchy sound to it. "Crappit" is used when something doesn't work out for you or doesn't matter. Or hurts. You can really use whenever you feel like it.
You drop something you say "crappit". You ask someone to explain something but find out that it's really complicated you say "crappit". Someone tell you something bad or sad you say "aaw crappit".