I don't understand.

At work I do prep. I only know that and fries. I work at McDonald's. Usually after I get dishes done I got take a 10 minute break and then I go to fries. The other day I was back there doing dishes and my boss comes back there and asked me how long it was going to take me. I was like I don't know. She said ok try to hurry because I need you on fries and you may not get a 10. I said me? She said well anybody. We were short handed. So I get done and go up to fries. She then starts sending everyone on a break. But me. It was about 20 minutes before I got off and after the 5th person she's sending on break I asked if i could have one and she said no. I'm thinking wtf why not? So then I said can i at least go take a couple of puffs off a cigarette? She said go take a 10. At this point it had been 3 hours since I had one. If i hadn't said anything she wouldn't have let me go. That's the only bad thing that has happened but it really irritated me.