For example: curl -svL -H "Content-Type: application/json" -d '{"test":"bar","hi":"xyz"}' http://localhost:8080/hook
It'll show up in your discord.
Expanding
Right now, all of the json types are defined in lib/proxy.go. If your json isn't a simple map[string]string, you can create a new type and add it to the file. You can see existing types in the docs.
Please add a test for each new type you add, so we don't break in the future.