hmmmmm, i'm just looking to carry as little as possible during the days.....well, i guess i will buy a pop, pour it into my mug, and throw away the cup.
We always fill our mugs on the way out in the morning. By the time we get to the park the mugs are empty, so we put them in a locker. Then when we go back to the resort we rinse out the mugs and refill them on the way back to the room.
I've refilled the mugs in the parks before and depending on the stand, paid for either a medium or a large drink. Whatever they say, I don't argue, I just hand them the mug and tell them to skip the cup.