Rectreem is a vaguely mammalian creature, loosely resembling a naked mole rat, with a tree growing out of its anus. The branches present on its head bear a resemblance to the horns of a goat, suggesting Rectreem may be based on a faun, a mythical being with features of both humans and goats. Fauns are associated with nature and forests, hence the Grass typing. It may also be a parody of official Grass-type Starter Pokémon, many of which have vegetation growing on seemingly unfavourable parts of their bodies. Its evolutionary line may also evoke the phrase "a stick up the ass". Much of its body is composed of its backside. Its shiny colouration is based on a blossoming cherry tree, or sakura.
The cheek pouch hidden ability is meant to imply that the pokemon has begun hiding food between its buttcheeks.
The pokedex describes rectreem giving their rivals "enemas" which is a holistic medicine practice where one empties their entire colon of waste by using warm water. The implication is that rectreem forcibly remove the waste from their rivals' colons to deny the enemy's tree of fertilizer and thus starving it.
Rectreem is a combination of the words rectum, tree and requiem.
Benpirin is a combination of shinrin (forest) and benpi (constipation).