I have a great tip for using your Refillable Mug, but first we need to review some things:
The Deal for $11.99 you get to buy and keep a souvenir mug and refill your mug with a drink for as many times as you like during the course of your stay at that resort for free (lets forget the used mug debate for now).
That said and given the rules here is what we do and here is the tip. We buy 1 Mug (for 5 of us) each trip and bring a 1 gallon Jug along from home (awkward when you fly). In the morning, when we go to the food court to get food for the kids we also bring the empty gallon Jug. Since there is no rule that says you cant share your drink with others or pour the contents of your Mug into another container (i.e. a Mug, a Jug or anything else) I pour about 12 Mugs of coffee, one-at-a-time, into the Jug (I know this sounds ridiculous as I could just put the Jug under the spout and fill it all at once but I dont want to break the rules). After the Jug is full, we grab a handful of sugar packets then fill the Mug with half-and-half (free of course) and head back to the room. While the kids are getting dressed, we drink coffee (ever have six cups of coffee in ½ hour what a buzz).
We usually take an afternoon break and go back to the hotel for a dip in the pool. Same routine, 12 Mugs of Coke or something else - from the Mug, into the Jug - then out to the pool. Since there is no rule against sharing your drink, we often pour drinks for anyone we meet at the pool then just refill the Jug (I think 3 times in two hours is our record).
Same thing when we get back from the parks at night except one Jug (maybe two) is usually enough.
When we get home that poor Mug is history as it is only good for the length of our stay. We have found that backing the car over a used Disney Refillable Mug pretty much does the trick. Hope this tip helps LOL.