Green’s Dictionary of Slang

muns n.

also munds, munns
[dial. mun, the face; thus mid-19C street cry ‘One a penny, two a penny, hot cross buns, / Butter them and sugar them and put them in your muns’; Grose (1785) traces it to Ger. mund, mouth]

1. [mid-17C–19C] the mouth, the jaws, the face, the lips.

2. [mid-18C] in ext. use, the whole person.

In phrases

black muns (n.)

[17C–18C] hoods and scarves made of lutestring (a glossy silk fabric) or alamode (a thin, light, glossy black silk).

rum muns (n.)

a handsome man.