This type of expression is called an onomatopoeic expression. i.e. a word, or words, or simply, as here, a collection of letters, attempting to imitate a sound.

excitement,

lack of a better word at the moment or

there are just too many things one want to say at the time, but can’t so…hmmmpphh, cuz I got my two points, I hope you get the answers you seek from this question! 🙂

I would even call it defiant indignation. Usually it’s used as a way to comically feign uppity indignation lol.

a) taking the huff with you over something you did or said or,

b) said person putting their indignant nose in the air, turning their back on you and stromping off in a mood!

For ex: If anyone tells mistake committed by any person for someone, he may react seriously in the above manner.