Help!! Need wagging work excuses FAST!!

REB

i showed up fifteen minutes late for work today and a manager asked me why i was late. i've been late before but have never been asked by managers in my own department for any justification, so i hadn't prepared any fake excuses so i just told her the truth, that i've been really busy at school and was exhausted from having underslept. she then said: that's not a good enough excuse. what is a good enough excuse?

traffic?

fire alarm went off in your building (if you live in certain kind of buildings I guess)

also, like, is it normal to be asked to give a reason to be late? i mean, if you had a good reason you would want to come out with it, right? when i was in elementary school you would have to fill out a form at the office where you checked the appropriate excuse off of a list, and i always checked "left late." just felt like that was the best way of expressing what would happen to me every morning: wake up, get dressed, breakfast, somehow by the time i was done i'm already late. remember one teacher hated it and would force me to check off another box. i've never had anyone scrutinize my reason for being late since then and it felt weird. i realize it's irresponsible and stuff but can't you just glare at me and carve a notch next to my name or something instead?

Yes it's normal.