I've always heard it in more of a political sense. An example for the cuck insult would be, Foo is a cuck because he likes to watch others come over to his hous

I've always heard it in more of a political sense. An example for the cuck insult would be, Foo is a cuck because he likes to watch others come over to his house and fuck his wife. When applied to political situations, Foo's wife would be the US and the others would be illegal immigrants. So Foo is a cuck because he wants illegal immigrants to come over and mess up the US. And I do believe that many of them are aware that it's a fetish, with many jokes about Foo's wife's boyfriend.