Interesting use of a profanity-laden (homophobic) phrase that's often used on the internet. Usually "being on someone's dick" means you like and defend that person. In this case, it's being used to say that you're criticizing that person, the complete opposite sense really. It's almost as if it has been lexicalized for this person to the point where the rather plain origin is no longer transparent to them.

#linguistics #lexicology #lexicalization #English