The Birthday Mezzo-Tenor is a fanmade birthday sing a ma jig. He is the same color as the dark purple one's shirt, has the same ears, hands, and feet, like all birthday sing a ma jigs, has black square eyes, has a voice mix between the teal and dark purple, a teal nose and a mouth that is the same color as the shade of green from the little one from the gold duet. He sings "Happy birthday" just like all the birthday sing a ma jigs. He signs in by saying "Hey birthday! Wassup?", enters song mode and isgns off the same way as the birthday tenor. He has the same color shirt as the lime green one's fur with polkadots that are the same color as the ghost's nose and the words happy birthday in orange lettering.
This is what he looks like.