Green’s Dictionary of Slang

bender n.2

[? the image of a drunkard (or drug user) as unsteady on their feet; or ? f. an image of bending a bow or elbow. Note naut. jargon benjo, a spree, f. Ital./Lingua Fr. buengiorno, a good day]

1. [mid-19C+] a bout of riotous drinking, often lasting several days and including random acts of excess, violence etc; thus on a bender

2. [late 19C–1910s] anything exceptional, astounding.

3. [late 19C] (US) a rampage.

4. [late 19C] one who poses as smarter than they are in the pursuit of hedonism.

In phrases

on a bender (adj.)

1. [mid-19C+] on a drinking spree.

2. [20C+] on any other kind of spree.

3. [1930s+] bingeing on drugs.