Green’s Dictionary of Slang

1. (US Und.) a male homosexual.

1949

Monteleone Criminal Sl. (rev. edn).

2. a term of abuse [late 19C use ? from stuff v.¹ (3)].

1890		Music Hall & Theatre Rev. 19 Apr. 7/1: Curate: ‘My friends, your language is something dreadful. Where did you learn it?’ — Navvy: Ga’rn, yer silly stuffer, yer don’t learn it; it’s a bally gift’.
1975		H. Ellison ‘Along the Scenic Route’ in Deathbird Stories (1978) 42: I’ve had it with these fuzzfaces [...] you remember when that punk stuffer ran us into the abutment?

3. (drugs) a smuggler who hides drugs in the anus or vagina.

1986

Sun. Times 26 Oct. 3: Customs investigators at Heathrow airport have discovered more than 100 Nigerians on flights from Lagos attempting to smuggle heroin packed inside contraceptive sheaths, which are swallowed or inserted in anal and vaginal passages. They are known to customs officers as ‘stuffers and swallowers’.