Green’s Dictionary of Slang

lower adj.

SE in slang uses

In compounds

lower house (n.)

[late 18C] the vagina.

lower mouth (n.)

[late 18C-mid-19C] the vagina.

In phrases

lower than a snake’s belly (adj.) (also lower than a snail’s belly, ...a snake’s belt buckle, ...the spots on a snake’s ass) [1920s+]

1. (Aus./US) as low as one can go.

2. (orig. US black, also lower than a midget’s ass in hell) depressed.

lower than the belly of a cockroach (adj.)

[1940s+] used of a person categorized as the lowest of the low.

lower than whale shit (adj.) [1960s+] (US)

1. extremely depressed.

2. (also lower than shark shit) of no moral worth.