When I'm angry (or any emotion) it's hard for me to 'fake nice'. I don't do it. I can't. If I'm angry at you, I will not pretend that things are okay and grimace as I grudgingly shake your hand.
I feel you should honor your emotions, your self, and also other people and their personal truth as much as you can in a situation. Sometimes people just don't like each other. That's fine.
I hate passive-aggressiveness, or doing things you don't want to do because someone is 'a friend' or 'in need' and then later throwing it back in their faces when they never asked you to do such a thing.
I'm all about speak your mind as soon as something comes up that bothers you.
Honestly, anger is very exhausting and it can eat you up inside. It can also be very productive and serves a higher/another purpose but turning it into a constructive energy is also very exhausting and can take lot of higher level life skills and let's face it, most people do not have those in abundance. We're only as magnanimous as our internal limits allow us, everyone has different resources (internal/external) to deal with life, issues, and anger.
As some others have already described, ENFPs can get extremely seething and know exactly where to hurt people the most. My anger can be white hot like fire but when I'm really heated I focus it with surgical skill. It actually really activates my Te and maybe to help control my internal Fi fire, I get super analytical about exactly how to 'resolve' the issue. I get so angry it's like it burns my compassionate nerve endings and other 'nice' humanitarian things that ENFPs are known for. All I can be at that moment is angry -- though I guess that's human nature in general.
On the flip, this actually makes me very productive and all 'effect change'-ish. I think this is part of the 'idealist' motivation -- when anger at seeing injustice motivates you to change the causes. I'm very much about getting at the 'root' of the problem when I'm angry. That is the ONLY thing that will appease me. Interpersonally and otherwise, sometimes just explicitly telling the other party how I feel and why can calm me almost instantly.
I think ENFPs have the nasty habit of having anger and other 'negative' (I know, value judgement) emotions and energy go inward and seep deep into our beings.
Being angry can get me positively batty. 'Cause when I get angry, I get pretttttty stirred up. It can seriously consume me in the moment.
The only way for me to cope has been to not let things bother me so much (HAHAHHHA, tell that to an INFJ or an ENFP -- HAHAHAHAHAHA). It's like I had to sever some nerves and just like losing the acuity of one of your senses your entire quality of life diminishes -- or rather changes. Kinda like how losing your sense of smell makes your palate much weaker (can't taste food very well).
But, I haven't felt batty in a long minute, my self-esteem is higher and more stable, and my mood in general is much better. I think there's also a definite link between anger and depression because I have not felt this normal and actually pretty good in a while. So in other sense, my quality of life has improved. So it's a compromise.
Until I develop those 'higher level life skills' and expand my inner resources, this is how I'll deal with anger and things that make me angry. It's a stop-gap, but it works.