Trunk People are a synthetic species of human-like creatures that have trunks on their faces. Scientists gave them trunks that allows them to have sex with both male and female partners.
History
They are first mentioned in the episode "Rixty Minutes" through two commercials regarding a ballot measure called Proposition XW2 that would allow Trunk People to get married.
A trunk person Morty is seen being treated at a hospital in the Citadel of Ricks in "The Ricklantis Mixup."