>>82601860Because I know this one guy.
He always takes MLP-related images he sees and reposts them.
I know one guy who did this shit on /v/, we'll call him the retarded derpibooru poster, whose posts mainly consisted of MLP crops.
I could identify him by the fact that the derpibooru ID was in the filename. Like for this one, if the link was
derpibooru.org/1012001, then the OP image would be 1012001.jpg. It's common sense.
I have a bit of a photographic memory so I know where this shit comes from whenever I see this shit again.