Why must you yell at me?!!!!!

My largest pet peeve is when people choose yell at me. If I didn't yell at you or do anything to harm you emotionally, physically,mentally or socially then why yell? Now I understand if you told me something four or more times then okay, but if you only told once then don't yell out me. The way I see it is that you just need to chillax, take a nap and get off my back!