When did drinks known as "sex on the beach","blowjob", and "screaming
orgasm" begin to originate? Where do these drinks come from and who
buys them? I'm trying to write a paper about the intrinsic sexism
found in the names of these adult drinks and I can't find any
information on when they came about and became popular.

Interesting study - I hope you'll update us when it's done. 

According to this site, the "adult" cocktails were invented from the
1960s onwards:
The History of the Cocktail
<http://www.drinkfocus.com/cocktails/cocktail-history.php> 

And here's another 1960s version: 
" The sexually liberated 60s spawned drinks like Comfortable Screw and
Screaming Orgasm."
<http://www.nzherald.co.nz/category/story.cfm?c_id=46&ObjectID=10357528> 

This site places it in the 1990s, and not earlier: 
"1990 AD The martini and the lounge make triumphant comebacks. On
their back arrives the pseudo-martini craze, whereas even a dead rat
served in a stemmed glass can be called a martini. This is also the
era of the ribaldly-named cocktail, including the Sex on the Beach,
Screaming Orgasm and Sloe Comfortable Screw."
<http://www.moderndrunkardmagazine.com/issues/04_03/04-03_history_of_hooch.htm> 

I do hope that someone would answer your question fully.

Comfortable Screw and Slow (from sloe) Comfortable Screw were amusing
takeoffs of existing drink names and ingredients. Giving ribald names
to any old mixture of booze is hardly difficult.

Having said that, my fave was a Dirty Girl Scout.

They're certainly older than the 90s - London, UK, cocktail bars were
selling Screws, Orgasms etc - and I among others drinking them - back
in the 70s.

thanks a lot for your help. I'm actually a college student in
switzerland and I'm taking a really great class about language and
society and how they effect each other. For our final paper the
professor asked us to answer an original question about language and
one of the topics was this one about how the names of some adult
beverages contain a sort of intrinsic sexism. The question is framed
like this: If you can walk into a bar and order a drink called "sex on
the beach" or a "blowjob" why can you order a drink called a
"misogynist prick" or a "heartless boyfriend"?
We never really think about the way we use language because of the
"fishbowl effect"...the fact that its always around us and always has
been, we're like fish existing in water without ever noticing it.

I'd be happy to post the paper when I'm finished with it if theres
interest... again thanks very much for your help.

If you don't mind me commenting again, I think the short answer to
your prof's question is that cocktails are supposed to make you feel
good and so is sex, thus the association between them. (And this, of
course, is also the association that exists in advertising and
marketing between almost any object and sex.) I don't think cocktails
called "misogynist prick" or "heartless boyfriend" would make anyone
feel good. Incidentally, how are these the opposite of "sex on the
beach" etc, which are quite unisex? It isn't as if cocktails have
names insulting to women, such as "gold digger" or "c...k teaser".

Can I just ascertain what Geof meant by "It isn't as if cocktails have
names insulting to women, such as "gold digger""? Gold digger is
essentially unisex - but Geof has said that it is a name that is
"insulting to women".  The very fact that gold digger should have
connotations associated with women is sexist in itself.

I think bartenders make these names up. Some catch on and some don't.

http://www.djcraig.net/lagunabeachwedding.html

www.djcraig.net