I think most of us have heard it before … someone imitates a stereotypical gay male by saying “Sthey there, Bruth?” I’ve also seen the name “Bruce” used by comedians to identify unnamed gay men, in much the same way that “John Doe” or “Jane Doe” is used.
How did the name “Bruce” get to be known as a stereotypical gay male name?
Maybe from Bruce Vilanch? Just a guess…
Trivia note, it was because of this that the character in The Hulk was called “David Bruce Banner,” and not simply “Bruce Banner.” And I can remember having a friend back in the late 70s who caught hell from all of us for being named “Bruce.”
Bruce Vilanch came along long after the name Bruce had this association with a stereotypically gay man.
I’m sure Bruce Lee, Bruce Springsteen, and Bruce Willis have something to do with the name now being de-stigmatized.
Just a followup: I’ve heard “Lance” used as a generic gay male name quite a bit, too. More recently, it’s “Todd.”
Lance Loud, the son in the groundbreaking PBS documentary series An American Family (1973), was one of the first openly gay persons on television.
And then there is lance as a slang term for penis.
The song “Big Bad John”, popular in the early 60’s, was parodied as “Big Bad Brucey Woosie” by somebody using this stereotype, which takes us back a notch further. I’ll bet it goes back a good bit further than that, though.
Okay, here’s my WAG on the topic…
Back in the 60’s there was a now famous beach music tune called Hey Baby (“I wanna know, if you’ll be my girl”). It was recorded by a guy named Bruce Channelle.
Well, I don’t know what Mr. Channelle’s sexual orientation was, but I do know that during that decade we used every excuse we could find to make fun of those who we thought were “queer”, and yes, I include myself in that “we” even though today I am very ashamed of myself.
As the OP stated, the name Bruce lends itself to that stereo-typical lisp at the end of the name (Bruth), and I think that DJ’s used that first name and the last name as a joke when they introduced the song on the air.
IOW, some guy might have said, “Bruce Chanelle?! (Chanel#5) Boy does that sound queer!”, and ran with it.
That’s my theory. Then again, I could be full of shit. 
Quasi
I thought that Bruce was the generic name for Aussies. Monty Python:
“Rule number one: NAOW POOFTERS”
I’m not aware of any gay connotations to Bruce here though, seems an American thing.
About 20 years ago when I was 11, I saw a television special about two gay guys, Bruce and Jeffrey. My dad noted some significance of the names, and it stuck with me ever since.
I remember a Hudson & Landry (60s US comedy duo) sketch in which a pro football quarterback is interviewed. Said QB was named Bruce, and spoke with a pronounced lisp, and in general acted exactly as one would expect a 60s comic gay stereotype to act.
Like Quasi, I suspect that H & L got the “Bruce = gay” meme from somewhere else; some older Dopers might remember earlier instances of this meme?
Ditto here in the UK, where the typical Aussie couple are often referred to as “Bruce and Sheila” - no gay connotations there … quite the opposite!
Julie
Perhaps it is because the name Bruce is easily lisped, which seems to form part of many gay stereotypes?
Grim
Bruce of Los Angeles was a male physique photographer in the 50s.
Homer: They’re embarrasing me. They’re embarrassing America. They turned the Navy into a floating joke. They ruined all our best names like Bruce, and Lance, and Julian. Those were the toughest names we had! Now they’re just, uh…
John: Queer?
Surprised I was the first one.
Homer: They’re embarrasing me. They’re embarrassing America. They turned the Navy into a floating joke. They ruined all our best names like Bruce, and Lance, and Julian. Those were the toughest names we had! Now they’re just, uh…
John: Queer?
Surprised I was the first one.
I recall that Johnny Carson, when he would need to mention a generic gay person in a joke in his opening monologue, would use the name “Bruce.” He was already doing this by the '70’s. I suspect that he popularized the use of “Bruce” for generic gay characters. He may have invented the tradition himself, or he may have gotten this from some early standard use of the name.
No, as already noted the use of Bruce in this way goes back way before the 70s. It was part of the culture in the 60s when I was growing up.
Some say that it may have come from Bruce Wayne, because of the covert homosexual relationship between him and Dick [Dick, ha, ha, snigger, snigger] Grayson. This was a charge leveled by Fredric Wertham in his 1954 book Seduction of the Innocent so it was current by then.
There’s also this bit of slang:
BRUCE LEE
Erect nipple (as in, a hard Nip).
And the second one.