Jim Macklin wrote:
You are
offering to pay for lunch at a place of the others choosing,
etc and that makes it a "for pay operation requiring a
commercial certificate.

But surely this wouldn't qualify; the purchase of lunch is both
incidental and coincidental to the act of flying; neither the act of
flying nor the purchase of lunch must necessarily and/or inevitably
follow the other, obviating the comp/hire clause?

You could be nicked on the paying of rental/loggable time (good will
applies), but not the hamburgers!

TheSmokingGnu