Why do my parents want me to do something the very isntant they tell me?

I may sound like a brat for all you parents reading this right now, but I'm just tired of my parents giving lectures everytime I don't do something the instant they tell me to. As simple as taking out the trash my parents just ***** about me being lazy. I tell them "Five minutes" or "let me finish this" then they act like I haven't done **** for them ever. I have a brother and he's older than me, but my parents never complain that he doesn't get **** done, they always ask me to finish his tasks. I'm sorry for the foul language, but I'm tired of the way they do these things.