One place I worked, I had transport problems for a few weeks and arrived 5 minutes after the stipulated starting time. I was staying late and more than made up for it.
One morning, one of the directors took a cheep shot of "we don't have flexi time here"
I replied "Your staff are always flexible, working late nights or heading off to site at short notice, so maybe you should." Our customer's sites were 12 hour days/7 days a week for several weeks.
Passed him the next morning and he didn't say a word.