This is a slang term with no known origin. It can be applied to just about anything---persons, missions, ships, and so on---when everything seems to be going wrong.

Since Klingons consider self-control a great virtue, declaring oneself to be cursed is comparable to an admission of weakness and utterly uncharacteristic (though not unknown).

To say that someone else is cursed, on the other hand, is to attribute weakness to that person. Accordingly, bI'Igh ("You are cursed, you are jinxed"; bI-, "you") is quite insulting.

In standard Klingon, the same idea may be expressed by saying Do'Ha'moHlu' ("be made unlucky" or "someone/something causes [someone/something] to be unlucky"), as in DaDo'Ha'moHlu' ("You've been made unlucky," or "someone/something causes you to be unlucky"; Da- along with the impersonal subject suffix -lu' means "someone/something [does something to] you").