Eme, La, n. — Green’s Dictionary of Slang

Eme, La n.

(US prison) the prison gang known as the ‘Mexican Mafia’.

1973		Hearings [...] of the House Committee on Internal Security 1237: The Mexican Mafia (EME), Nuestra Familia, and the Aryan Brotherhood (AB).
1993		K. Scott Monster (1994) 343: Next to you is an A.B. and on the other side is an E.M.E.
2009		J. Stahl Pain Killers 48: Inmate jumped into La Eme 11/06.
2019		D. Winslow Border [ebook] ‘Whose car are you in?’ ‘I’m doing my bones with Eme now’.