Ok here we say are ideas on why the chicken crossed the road! And you are not allowed to repeat the joke like:

Q.Why did the chicken cross the road?
A. To get to the other side!

Yeah no joke answers. Like here is mine:

Because he got in a fight with a friend and still wanted to chat with him every now and again but his friend hated his guts so he crossed the road to let out a cry.

See kinda depressing huh!