Flickr doesn't break down views, so, for all I know it could have been bots doing image recognition or a single guy in his bedroom clicking on certain pictures 100x a day.

But yeah.... "links shared on forums" was always my leading theory.

In some cases, I'm sure the thumbnails enticed extra clicks. But some of the pictures just had a bustier than average woman in the background or something. It's not clear to me that the thumbnails were enticing.

(99% of these people were my IRL friends as well, so I wasn't really trying to take salacious pictures....)