It's the third inside joke tied with beans.

1. what you said, "I head people on lemmy upvote everything so here is a can of beans"
2. lisa white screen meme "A twitter screenshot is not a meme" -> spammed screenshots "is not a meme"
3. fusion of "is not a meme" and BEANS

We are at stage 3, not stage 1 :D

edit: the important part of stage 2 was the "is not a meme" after originally something about screenshots, customised to your app. Sometimes it was about something else, but always ended in "is not a meme"