Seat Belt Extender

But, of course, the obese should always have their travel agent note
"strap passenger" (airline lingo for someone so big the seat belt
won't go around them), or they should note that under special requests
if booking on-line.

I've never heard of "strap passenger". I've also never seen any type of
notation on the SPIL that indicated the passenger requests an extender. We
have extra onboard, besides the demo one. It's not uncommon for more than one
passenger to need one.