Ran into a n00b at Aldi trying to figure out the cart system. (There's a giant how-to sign right over the carts, but it is exactly parallel to the crosswalk so he never saw it anything but edge-on.) This is why I made sure both slots of my quarter keeper were full. (They've been doing it quarter-less lately so I half expected an oldbie to have been caught by surprise.)
Dude tried to offer me a dollar in exchange; I explained that the tradition is to just leave the gift quarter in the cart.