Green’s Dictionary of Slang

stretch v.

1. [17C–1960s] to hang, to be hanged; thus stretcher n., a hangman [abbr. SE stretch one’s neck].

2. to lie.

3. [late 19C+] (also stretch out) to knock down, to kill [SE stretch (someone) out on the ground].

4. [1940s+] of a man, to have sexual intercourse [? link to stretch leather under leather n.].

5. see stretch (it)

6. [2000s+] (US drugs) to adulterate and extend the volume of cocaine with baking soda, etc.

7. (US drugs) to fill a vial of crack cocaine.

In phrases

stretch someone’s neck (v.)

[mid-19C–1950s] to hang; thus neck-stretching n. and adj., hanging; get one’s neck stretched v., to be hanged.

stretch (the) hemp (v.) (also pull hemp, stretch a line) [the hempen noose]

[mid-19C–1950s] to be hanged or to hang oneself.

SE in slang uses

In compounds

stretch one (n.)

[1930s] (US) a large glass of Coca-Cola.

In phrases

stretch (it) (v.) [SE stretch the truth]

[late 17C+] to exaggerate, to lie; thus stretching n., lying.

stretch out (v.) [jazz use stretch out, to play to one’s limits, with no restraints other than one’s stamina and skill]

1. [1950s–60s] (US black) to live one’s life without restraint, to act uninhibitedly.

2. see sense 3 above.

stretch some jeans (v.) [the removal of one’s jeans or trousers]

[1980s+] (US prison, esp. homosexual) to have sexual intercourse.

stretch someone’s breeches (v.) [the bent-over buttocks tighten the cloth that covers them]

[late 19C] to administer a thrashing.