Plasticine

Your fiancée seemed unusually excited on her return from the shopping trip, rushing over to squeeze next to you and whispering "guess what I got for us?" in your ear. Her hand sliding up your thigh suggested it wasn't a new flavor of ice cream.

Thinking fast, you responded, "I don't need anything but you!"

Kris's smile brightened and she says, "Yes, that's it! Only better!" and barely managing to wait for your confused look she tossed an un-labeled plastic tub on his lap. "I scored us some plasticine!"

"Holy shit!" You had read about this stuff in some Reddit posts, but it was supposed to be really hard to find and definitely not legal. Yet, here was a tub of it on your lap.