The famous (to me at least) 'Fruit Slime' scene that lives rent free in my head
In which Vanitas' apprentice asks him what one of the various Foods of Uncertain Variety that they serve at the Org is, and his answer is simply 'fruit slime', no elaboration
(btw, I recommend that you read the fic in order! it is part of a series, with the first part being 13 GOTO 7. Although it's still an excellent read read out of order (I did that accidentally! whoops), the first part explains a lot of things you might otherwise be confused about!)
I am still not sure what the fruit slime even WAS, as both Vanitas and Felix are unreliable narrators who often lack the experience needed to properly identify many mundane objects... It could be a jam, or a jelly, or even a puree, or it could what I drew here which is basically one of these, but like more in the style of a cheapo one you get at the store with all the fruit settled at the bottom.