Caption reads: "Nothing to see here, folks, just a very normal venn diagram."
Depicted:
A venn diagram. At the three extremes are:
1. A kitchen knife
2. A stick of butter
3. A fly (insect)
In the sections combining:
1 & 2 a butter knife
2 & 3 a butterfly
1 & 3 a kunai (i.e. a Japanese weapon, popularly thought of as a thrown weapon, here being construed as a flying knife)
In the central section is where all fields combine is a balisong, also called a butterfly knife.
