I designed this when I started going to Busch Gardens on a regular basis. All amusement parks and zoos sell these refillable cups that you bring back whenever you return. These are not cheap, I think the price is now like $11.99 this year (2018). Refill is about a dollar.

So I set one of these down at a show I attended and walked out without it. This is my solution. I wear this cross body and there is plenty of slack to take a drink from the straw. I cannot tell you how many of these I made or how many pictures people have taken of these in the park.