If you've ever filled one of those 'Cheeki' coffee cups, or virtually any other reusable coffee cup, you've definitely come across the issue that when it's 'overfilled' it will overflow when the lid is put back on. There is a simple solution to this problem, and you won't believe just how simple it is.
Before you screw the lid on, pop the cap. That's it.
This will allow the air to escape as you screw on the lid. Boom! No more spilling! This works because with the lid closed, the air pressure forces the liquid underneath it to displace as it's lowered into the cup, by popping the lid, the air can escape allowing the liquid to use the space within the lid cavity.
You wouldn't believe how many times I've had one of these overflow because a Barista doesn't know to pop the lid. A simple problem, and a simple fix.