The hand-puppet belonging to homosexual/transsexual/homosexual again South Park school teacher
Herbert Garrison.
Mr. Garrison has often used the doll as an expression of his own repressed feelings or beliefs, including homosexuality while he was still closeted and his racist leanings when Mr. Hat was a member of the KKK. More commonly he is used as a teacher's aid via
ventriloquism.
Due to
Garrison's southern drawl, he pronounces the name as "Mister Hay-ut".