He mean on a ship I guess. It was a common superstition in the age of sailing.
[The One Who Revels in Chaos]
Spoiler!
I'm a good boi 
Comment by Eden Gremory on The Knight King Who Returned with a God - Chapter 52
1 Reply
@Eden Gremory there was and still is tje reason for this best example US military studies of integrating women in military platoons.