Refillable sipper cups at Disney

Busch and Universal parks have them. Heck, Cypress Gardens has them. So why doesn't WDW have those souvenir sipper cups you can buy once and get cheap refills on?

There's the coffee rumor (keep your cup all day and refill for free; it's semi-true but I find it uncouth). And there's the resort mug, which really is good for the length of your trip. But no sipper?

Well, there is a sipper, and I always forget about it. It's only at DAK. Refills are a bargain rate $1.00 (I think) and I just recalled recently that I used to have like two of these sippers. Both are now missing, so I should buy one. These days I spend a lot of time at DAK, and those soda prices add up.