I once flew from Newark to L.A with a larger guy. He wasn't so big but the stock seat belt didn't fit him so instead of embarrassing himself he just tucked both sides of the belt under his gut and pretended to be buckled in. I told him I'd happily ask the stewardess for an extender but he said he has his own but accidentally packed it in the wrong bag. He didn't like asking for one and making a scene. Felt kinda bad for the dude but we took off, landed, and had a few bumpy patches along the way but he stayed in his seat as if he were glued in so all worked well.