What does "watch your six" mean?
Does it mean "watch your back", like in a dangerous area?
Your intuitions are correct; the phrase 'watch your six' does indeed mean 'watch your back'.
It refers to the 6 position on the face of a clock. If you were standing in the center of a clock face, facing the 12 position, the 6 position would be immediately behind you. From Wikipedia:
Using this analogy, 12 o'clock means ahead or above, 3 o'clock means to the right, 6 o'clock means behind or below, and 9 o'clock means to the left. The other eight hours refer to directions that are not directly in line with the four major directions.
Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
Would you like to answer one of these unanswered questions instead?