you've never come into work early and had someone say
"what the hell are you doing here?"
I work on flex time, whenever I start I work 8 hours then I leave.
My start time depends on how late I stayed out the night before. When I work 9+ hours no one says a word, but when I work 7 hours, I need to remind the others that I worked 9 hours the day before.
I did start an hour later than usual today, not because I didn't set my clock, but because I didn't want to get out of bed.