I find that my chameleons get a lot more aggressive and revert to instinctual behaviour after spending time in the sun. The typical chameleon "staggerstep" tends to disappear after a short time in captivity, but returns the instant they get outside. Normally docile animals regularly flare and attempt to bite after getting a good shot of natural UV.
The funniest thing is when they think passing aircraft are predatory birds.
Revenge is a dish best served cold...
With a side plate of steaming entrails,
And a nice Bordeaux!