A pejorative used by alt-Right conservatives to insult moderate Republicans. It implies they have sold out and is similar to the term RINO. The term is a combination of ‘Conservative’ and ‘cuckold’ (one whose wife is cheating on him). It implies that those moderates are weak and effeminate.
The term originates from the white-supremacist blogospher which started using it in 2015. The term gained favor during the 2016 Republican presidential debates and has continued through the presidency of Donald Trump.