For extremes there's always another option, this actually happened to me about 20 years ago, in a large supermarket...
Ever so nice old lady: "Excuse me, but you could you possibly pass me that jar on the top shelf, that I can't reach?"
Me: "Of course, no problem at all, here you are!"
Old lady: "Thank you so much. Now could I possibly ask you to loosen the top for me, as I always find it very difficult?"
And I did.
If I'd had time to think about it, I'd have considered the trouble I might get into if I'd been spotted, if she'd not been the sweet old lady she seemed, or if she'd changed her mind and put it back. But sometimes, you have to go with your instincts.