Bringing up one or two front feet up to their body
Bringing one or two feet up to their body is a defensive move for chameleons. They are feeling threatened. It can be as minor as annoyance where you put your hand in their cage and they lift up one hand with a look of distain towards you. When they are more seriously threatened they will add puffing up their body and gaping to warn you away. At the highest level of threat they will pull both of their front feet up and sway on their hind legs. This is to allow them to bite in any direction you come towards them.
Meaning: Your chameleon is feeling annoyed or threatened and is feeling like they have to defend themselves
Possibilities: It is pretty clear. If they are brining one or both of their hands up to their body they are feeling threatened.
Solution: Stop your intrusion into their cage or stop whatever other animal or chameleon is concerning them. This can be another chameleon in the cage or in visual range, a bird out the window, a dog running around, or you putting your hand in their cage. Whatever is causing the stress, remove the source and this behavior will go away.