Koichi is angry with his workers because they don't wash their hands and gargle, regardless of how many times he's told them to do so.
Can I borrow your bathroom?
You can’t use a washing machine for Tofugu T-shirts. You have to wash them by hand.
You remember how 洗う is "to wash"? Well, when you wash your hands you're doing hand washing.
The readings are the vocab readings 手 and 洗う put together.