From the looks of this video, it definitely seems that monkeys can feel insulted.
This kid was apparently taunting the monkey, before giving it the middle finger. The monkey didn't take that crap & gives him a 4-foot flying dropkick. The guy looks like he can't believe he got knocked over by a monkey kick.
As much as I love discussing a wide variety of topics on this blog, I never get tired of amusing monkey antics.