Mystery Knob. What Does It Do?

What does this mystery knob do?? 🤔 There's a knob next to Rebecca's nightstand in our stateroom on the Celebrity Constellation. It spins. It clicks. And as far as we can tell... it does absolutely nothing. So I need your help, folks. If you sailed on Constellation back in her early days, what did this knob actually do? And if you've never been aboard, what do YOU think it did? Secret passage? Direct line to room service? Ocean volume control? Drop your best guess in the comments. The sillier the better! 👇 #celebrityconstellation #cruisetok #cruisehumor #cruiseship #mysteryknob