To prevent accidental button pressing when you're using iPod shuffle, lock the buttons (this is similar to using the Hold switch on other iPod models).
To do this, press and hold the Play/Pause button for 3 seconds. The LED will flash orange three times to signal that the buttons are now locked. While the buttons are locked, you will not be able to adjust the volume or pause playback.
To unlock the buttons, press and hold the Play/Pause button for 3 seconds. The LED will flash green three times. You can now adjust the volume, change songs, or pause playback.