Green’s Dictionary of Slang

drop off v.1

[fig. use of SE]

1. [late 18C+] to die.

2. [mid-19C] to retire.

3. [1930s] to kill.

SE in slang uses

In phrases

drop off a style (v.)

[1990s+] (W.I.) to lose one’s sex appeal.

drop off the hook(s) (v.)

[mid-19C–1930s] to die.

drop off the shopping (v.)

[2000s] to defecate.