As an airline captain, I once boarded a flight and introduced myself to my new crew, who were relaxing in 1st class awaiting passenger boarding.
I have had a "bad knee" since high school football (needing a waiver to enter AOCS) and have had many subsequent re-injuries and knee operations. Thus I had learned that when something "wasn't feeling right" with my knee, not to fight it and risk tearing something further, but to just immediately drop to the deck!
After greeting and briefing my new crew, I pivoted to proceed to the cockpit. My knee popped and I immediately – in full uniform – dropped to the aircraft aisle floor. Fortunately there were no passengers yet on board to witness this, but my new crew was ready to bail!!!!
Even though I immediately stood up uninjured, it took an awful lot of explaining and assurances before my crew was ready to fly with me.
(Years later, we had many laughs about it.)