It's kinda lemmy lore I guess.
Beans was a wave of shitposts from about 16 months ago where poeple kept posting a bunch of beans in various forms and the whole feed was mostly beans.

You'll also stumble upon the "3 days no poop" thing where someone asked a question in asklemmy I think about how to avoid shitting for 3 days.
I think they later deleted their account, but they were very mysterious about why and people genuinely came with ideas for them and it snowballed into its own thing.

Unrelated, but similar to the poop knife, if only in the inside joke / lore kinda thing.