"Action" is a placeholder word for any noun (or sometimes verb) that is clear by context but which the speaker is too lazy to remember.
As in:
  • "Let's fire up the action at the spot." equals "Let's go to Hank's house and play Starcraft."
  • "Let's do some lunch action." equals "Let's go to lunch."
The "lunch action" construct is a way of making lunch (and you) sound hip and with it because you're down with "action."