It's a Nazi character from an American show, who was always terrified of being sent to the Eastern Front in WW2.
I realize that some not-so-smart people will continue using it out of spite, even after reading this. I'm not going to try convincing anyone personally but at least those people will have to go to sleep every night knowing this.
The only "not-so-smart" people are the ones that think an imaginary character from an 20+ year old tv show is a horrible term.
I just don't like the term, not only because of its association with the character Klink. It's an "endearing" racial slur for the Klingon people, I guess, but it annoys the targh out of me everytime I hear it. I don't really say anything or make a big deal out of it because it seems I'm the only one bugged by it. It just sounds stupid to me. But like I said, I don't throw a fit over it, I just don't use it myself and hope it catches on (it so obviously won't; the term is here to stay forever).