Clownbombing 

Derived from photobombing, clownbombing means to respond to any social-media discussion by posting an unsettling photograph of a clown, with no text or caption whatsoever. When someone responds to your clownbomb, the only response should be a different clownbomb. This repeats.

She spent sixteen days clownbombing every Tweet posted by Bill O'Reilly.

Clownbombing by King in Yellow February 23, 2014