Oh, you think showing up 20 minutes late is a big deal? Yeah. It is. You’re given a shift with a starting time. Aside from a few problems that might come up once in a great while (car trouble, alarm fail, some sort of emergency), you are capable of getting to your job on time. Children are capable of reading a clock; if you’re old enough to have a job, you are too - and by the way, your lateness often inconveniences your coworkers and may have something to do with why they dislike you.