Why does anger feel so good?

Ok.. so basicly I am 20 years old... and I have never been in a fight.. (before today).. anyways.. Its not like I have never been angry.. But..I allways try to hide it..I mean I was bullied a lot...especially in midddle school.... But today was different... (Its a long story so im not really gonna talk about what pissed me off) to be honest I cant even remember the exact moment I exploded...but...this "guy" pissed me off so bad... that I couldnt hide it anymore... I just exploded.. and kicked his ***...its like all this anger I had built up over the years was all realeased... And it felt great... all the rage...all that anger flowing through my body I cant explain it...but It felt good... I felt like the HULK...in a sort of way... anyways anyone can explain it??