One of my jobs in the Navy was to give the general public and our service members tours of the USS Constitution. Before taking people down below, we warned our visitors to watch their heads climbing up and down the decks due to the low over hang. The tour guide, first to the top, gets to see how many people have not heeded his advice.
On one tour I watched almost an entire group of junior Naval officers hit their heads one after another as they came up the ladder well. Curious, I asked their commander what their job was...
… he replied!!!