Why does cham tail go straight?

[BallstoWall30]

Hey I got a question.... I been watching my Cham walk around his cage today, and he been making his whole body got straight, and his tail too. Like completely straight even if he is upside down.... Why do they do that?

 

[KarmaChameleon1337]

I've heard it's both a self defence thing to make them leaf like and a mating thing.