mummy, n. — Green’s Dictionary of Slang

mummy n.

[SE mummy, a wrapped, embalmed corpse, orig. Egyptian]

(US) an incompetent.

1831		Navy at Home II 127: Smallnouse [...] declared [...] he'd not stir a peg that way; but would go home to the tavern and await their return; the ladies asking what they should do with such an old mummy as that.
1906		E. Pugh Spoilers 206: Gimme a ’and, can’t you, ’stead o’ bleatin’ there, you mummy!
1908		A.N. Lyons Arthur’s 101: Oh, you mummy!
1908		T.A. Dorgan in Zwilling TAD Lex. (1993) 58: Throw that mummy out — he’s a terrible piece of cheese.
1915		M.G. Hayden ‘Terms Of Disparagement’ in DN IV:iii 202: mummy, idiot. ‘He sat there like a mummy’.

mummyfucker (n.)

2011

J.J. Connolly Viva La Madness 193: He’s a drip who couldn’t hold up a wet handkerchief, let alone a deranged mummyfucker like Jesus Zambrano.

mummyhead (n.) [-head sfx (1)]

(US black gang) a fool.

1991

L. Bing Do or Die (1992) 120: Damn mummyhead. Think he a hard case.

mummy pussy (n.) [pussy n. (2)]

(US black) a woman who does not respond during sexual intercourse.

1992

in T. McMillan Waiting to Exhale in Major (1994).