MARMITE MOTORWAY the anal passage ...playground sl.
MASHED UP drunk, pissed ...c1990 UK sl.
MEESH a skinny little runt who acts like he goes looking for a fight every two minutes ...c1990s Welsh playground sl.
MEFF a dirty, smelly individual; a person with disgusting habits
...c1960s UK playground sl.
MEFF a vagrant ...c1960s UK playground sl.
MIFF female genitalia or pubic hair ...c1970s UK playground sl.
MILLENNIUM DOMES breasts ...UK playground sl.
MINGE the female pudenda ...1950s Brit. sl.
MINGIN(G) smelly, disgusting, ugly, horrid, putrid, gross ...playground sl.
MINGIN(G) ugly ...playground sl.
MITHER to complain, to nag, to bother or prevaricate ...Eng. dial.
MONKEYBACK a man who dresses in formal dinner clothes ...1928 US Black sl.
MONKEY BITE a hickey, a mark made on the skin by amorous biting ...1942 Amer. sl.
MONKEY DICK Vienna sausage; frankfurter, hot dog ...1965 Amer. sl.
MONKEY DICK a stupid or contemptible person ...1988 Amer. sl.
MONKEY MAN a weak and servile husband ...1924 US sl.
MOSSA! Well! Well! ...1981 Irish sl.
MOUTH-HARP a harmonica ...Bk1913-17 Amer. dial.
MR. CHARLIE a White man considered as an oppressor; any White man; used contemptuously ...1928 US Black sl.
MUCKER-UPPER a bungler ...1942 UK sl.
MUCK SACK a lazy person ...1959 US sl.
MUCK STICK a shovel ...1908 US sl.
MUCKSAVAGE a country person ...1998 Irish sl.
MUFF a woman, usually with an implication of promiscuity ...1914 sl., orig. US
MUMP-HOLE an unofficial place of refreshment for patrolling police officers, as hospitals, cafes, shops, etc. ...1983 Brit. sl.
MUNG dirt, muck; anything filthy or distasteful ...L1970s teenagers' & students' usage
MURDERATE to murder; to defeat ...sl.
MUTANT a clumsy, foolish, or otherwise unpopular individual (generally used by adolescents) ...sl.
MUTT 'N' JEFF deaf ...L1940s Brit. rhyming sl.
MUTTON a strumpet ...1599 obs. sl.
MY LAND O' LIVIN'! an exclamation of surprise among women ...Bk1913-17 Amer. dial.
NAPPERKIDS kidnappers ...Bk1913-17 Amer. dial.
NARROW-ASSED having slim hips; thin, skinny ...1916-22 Amer. sl.
NARROWBACK an Irish-American; used contemptuously ...1957 Amer. sl.
NASTY, THE sexual intercourse ...1967 Amer. sl.
NEVER IN ONE'S PUFF never in one's life ...c1880 tailors' usage
NING-NONG a fool, an idiot ...Aust. sl.
NIXIE! no! ...Bk1913-17 Amer. dial.
NOINTER a mischievous child; a brat ... ...Aust. sl.