Putting with the flag in?

Thought it must be a euphemism for the monthlies.

Is the flag red or have I badly misread your latest euphemism?

I shall bow to saddo's greater knowledge of these matters.

silly Americans ruining the fun again

Do they still insist that there be grass on the pitch?

It's just like playing your tee shot or approach shot with the flag in, only on the green.
It is, of course, optional and one of a range of rule changes intended to speed up play.