Giant Playing Cards
If you're big into cards, I've got something huge for you. These giant playing cards come as a 52-strong deck whose members each stand in at 11" tall x 8" wide. That's large enough for Grandma to see the suits and denominations without her glasses! ... But probably too heavy for her to hold up more than one at a time.
If you've got the arm strength, you can certainly use the giant playing cards to play cards, but the heavy duty card stock they're printed on also makes them suitable for party decorations and costumes.