Temporal effects on social acceptability

This is really an extension to a previous post from back near the start of this blog. I was hungry this morning and ended up going in to McCrap for breakfast (classy, I know). But while I was sat there eating my grease-in-a-muffin, I noticed a businessman in a suit, clearly on his way to a well-paying job, getting up and leaving. And that felt absolutely normal. But were that exact same man leaving that exact same (and I use the word cautiously) restaurant at 4pm, it would have seemed rather strange. At 11pm? Unthinkable. But at 9am on a weekday, McCrap is an huge mélange of different people. From the well-heeled businessmen, through the parents entertaining their young children all the way to the chavs and the homeless.

It seems odd to me that something that is perfectly acceptable can seem completely unthinkable just a few hours later. I can't think of any other examples off-hand, but I'm sure there must be loads...