Mammals both produce milk and have hair. Ergo, a coconut is a mammal.
I know you’re being facetious, but this is an actual issue with morphology-based phylogeny.
*leans over and whispers to person beside me* what are they talking about
*leans over and whispers back* Human ability to quantify and categorize natural phenomena is sketchy at best and wildly misleading at worst
Basically we like to say something is “a fish” if it has fins and gills and lives in water but different things we call “fish” are genetically less related to one another than a dog is to a toad or a parakeet so it’s a nonsense word. Similar is true of “reptile.”