l.b.j., n. — Green’s Dictionary of Slang

l.b.j. n.

[? joc. ref. to US President Lyndon Baines Johnson (1908–73) or from the nickname for the military prison in Vietnam, Long Binh Jail]

1. (US drugs) LSD.

1982		AS LVII:4 289: When LSD is mixed with other drugs [...] [s]uch mixtures are today called [...] LBJ.
2001		ONDCP Street Terms 14: LBJ — [...] LSD.

2. (US drugs) phencyclidine.

2001

ONDCP Street Terms 14: LBJ — [...] PCP.

3. (US drugs) heroin.

2001

ONDCP Street Terms 14: LBJ — Heroin.

4. (US) a large penis.

1971

B. Malamud Tenants (1972) 145: Even though you know you are well-hung and your LBJ salutes when it sniffs ass.