If you are talking about the shape of an object... A 'curl' is a twist or spiral in an object - usually for smaller and softer objects such as hair, fur, or fabric. A curl usually turns inward. A 'crooked' object is something that is bent or misshapen. For instance a tree branch can be crooked. Crooked objects are often old or poorly made, for instance an old house can be crooked, as can the fingers of an old person. A 'crook' usually means a criminal or untrustworthy person though. It is unusual to describe a specific misshapen object as being a 'crook.' Hope that helps. :)

We can't answer this question because we don't have enough information. What is the subject? What is the context? If you can give us some sentences and situations, we can suggest the best words to use.