When we go out with our toddler (which is frequently) we often get milk in a paper cup with a straw. If the restaurant doesn’t have bendy straws it’s usually too long to drink from keeping the cup safely on the table, or even in his hands.
Luckily, my wife and I both usually carry pocket tools with foldable scissors (a Mini Leatherman for me, a small Swiss Army knife for my wife) and we can easily cut a section of the straw off to make it fit. It also may be best to put the cut end in the cup if you weren’t able to get the cut smooth. Then the kid can take care of himself!