Cloppers are fans, who "fap" to the animated TV series My Little Pony - Friendship is Magic./Equestria Girls.
It doesn't matter if they "clop" directly to the series or to fan-made Rule 34 material of the show.
Jack: Hey! What are you doin'?
Alex: *Clopps* to a picture to Rainbow Dash*
Jack: You hate the show, but you are a Clopper...