Yes, straws. Simple, I know, but having these on hand makes a word of difference, just ask your makeup artist. Use a straw to keep your gloss from disappearing each time you take a drink.
They are also easier for those of us who are, let's say, accident prone. If you are super clumsy (we all know who we are) try a cup with a lid + straw to make spills even less likely. Adding this item to your "day of" list of necessities is simple + cheap and you will definitely use them!