Bash script to switch Pulseaudio sinks

Who doesn’t love using the keyboard even for simple things like switching the output (or sink as pulseaudio calls it) for you audio? My setup is a set of external speakers, a monitor with rather bad speakers and plugged into the monitor at all time my headphones. That makes three sinks which makes my script a bit more complicated than a simple toggle to the other (i.e. IDLE sink) would be.