You can do some pretty cool things in space. Like float in zero gravity, for example. Or eat in zero gravity. Or tweet in zero gravity. But there are plenty of things astronauts can't do in space thanks to that weightless environment. Which is sad, but they'll never let it show--because astronauts can't cry in space.
The Atlantic picked up on a tweet from the International Space Station, in which astronaut Chris Hadfield explained that our eyes will produce tears in space, but it isn't exactly a pleasant experience. Without gravity, tears don't flow downwards out of the eye and wash away irritants like they do here on Earth. They actually conglomerate into a little ball of liquid that hangs out in the eye. According to Hadfield, space tears sting.
When those space tears build up enough liquid mass, they'll actually break free of the eye and float around. Perhaps that counts as non-conventional crying, but who wants to cry when the very act stings the eyes? Astronaut Andrew Feustel got a flake of anti-fogging solution in his eye five hours into a seven hour space walk back in 2011. Tears weren't going to help get it out, so he had to rub his face against a block of foam inside the helmet.
Sad as it would be to float around in space without the ability to cry, we'd miss showering even more. Since a traditional showerhead doesn't work in a weightless environment, the ISS has no shower. Astronauts just have a spray nozzle and washcloths to clean up with. Gravity, you're the best.