I was twenty minutes late but my boss didn't mind.
Why were you late for work?
I went out late last night, had a slight hangover this morning.
You should not be out partying the night before work, that is what weekends are for. You need to behave more responsibly and remember that you are a paid employee and expected to show up on time.
You can't expect me to wake up at eight. I'll quit if you're going to use this against me.
I don't employ you but I am sure your employer will care when you don't do your job on time and expect to be paid for it. You should be more responsible or find different working hours.