The word "crooked" means "not straight". Specifically, people use the word "crooked" to talk about things that are:

• supposed to be straight, but are leaning to one side instead:

Your tie is crooked.

• bending in different directions with different angles:

They followed a crooked path through the woods.

Things that are bent smoothly, like a rope, aren't usually called "crooked". Things like that are called "curving" or "winding".