Let's say you have a pretend Gmail username like "example@gmail.com." If you add ".cc.cc" to this username, you can make a special address like "example.cc.cc."
When someone goes to this address, they can choose how much money they want to send and write a message to the person they're sending it to.
For example, if someone visits "http://example.cc.cc" and wants to send $10 along with a message, they can pick the amount and write the message.