It also serves as a handy handle to insult someone's virility or manliness that fits better in a tweet.
I wonder how much Twitter influences which new slang catches on. 'Bae' is a convenient three letters. For that matter, 'SJW' and 'MRA' are nice and short. You can get each term into a tweet, twice even, without using up much space.
Start throwing around 8 or 10 letter terms and no one is going to tweet them enough to quickly force them into culture.
That's precisely the intended meaning, that one literally or figuratively enjoys being taken advantage of.
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.
[1] https://fivethirtyeight.com/features/dissecting-trumps-most-...
like, if he called him a douche, i'd assume it was to say he doesn't care about his obligations to the american people and is only interested in helping his rich buddies... not that the prankster was too lazy to come up with anything other than a gross and generic comparison to female hygiene.
If that's not the definition of being "cucked" I'm not sure what is.