Perhaps no celebrity's Instagram feed highlights the special nature of the medium's commenters quite like Rihanna's.
Commenting on Instagram is different from commenting on Twitter or Facebook. First, it's more difficult to track a single user's comments on Instagram than other social networks since they're not all centrally located on a profile page. Thus trolls who constantly reply to or harass a celebrity on Instagram are harder to suss out, which probably makes everyone comment more openly.
While web browser interfaces exist for Instagram, users typically comment via cell phones, which can type all-important Emoji icons. This allows them to get expressive in so many unique ways. Here's a closer look at the Instagram commenting phenomenon as viewed through badgalriri's feed.