To specifically which sex acts to the terms “to lay” or “to get laid” refer? Obviously, it can refer to “missionary” position sex between a man and a woman. Does it also refer to gay sex? Anal or oral sex? Can the terms also apply to masturbation or bestiality or non-genital sex e.g. s&m? And is one person “laying” while the other person “gets laid”? Are there regional or cultural variations in meaning?
The term goes back in print to the 1600’s, although you didn’t exactly spell it out back then.
There is a print cite from 1786 that refers to it in no uncertain terms.
Most historic literature would talk about male/female probably “missionary position” sex.
That’s a problem with euphemisms, they can be pretty broad. This one, though, refers to sex between two people.
Compare to “sleep with”. Who actually sleeps?
Peace,
mangeorge
The term is actually used in the bible, isn’t it? At least in translations of that book.
Not quite. The Bible uses the expression “to lie with” as husband and wife. That old lay/lie trap has caught you again.
Biblical allusions to coitus are: came in unto her Gen 38:18, and he lay with her II Sam 11:4, uncovered her nakedness Lev 20:18, he knew her (sorry-no ref) KJV
I suspect there’ll be huge regional variations…sacred texts aside, I’d generally say that here, it means casual heterosexual sex. More specifically, casual sex which was intended, ie the participants went out with the full intention of finding somebody and sleeping with them, rather than ‘it just happened’ scenarios. It certainly doesn’t include oral sex ("…but he didn’t actually get laid…")…if it’s casual heterosecual anal sex, then I guess it becomes a topic for all-out bragging anyway 
. I’ve no idea what its common usage is among gay people. Oh, and it’s always ‘get laid’, never ‘lay’.
I’m not a linguist. The usage I’m familiar with requires two (uh, or more) people, unless you’re being terribly ironic. I have heard gay friends use the phrase plenty of times. In my experience, both partners get laid.
I’ve never heard it used referring to bestiality or non-genital sex. I have heard it used for mutual oral sex (“69”), but not for merely recieving oral sex.
I think the phrase connotation is non-oral, genital sex between two or more human partners.
I’ve lived in the midwestern, southeastern, and (currently) southwestern regions of the USA, and the usage seems to be identical.
Surely these are mutually exclusive? Or do you have a special talent you wish to share with us? 
No, it’s common to hear or read sentences to the effect of “I’d like to lay her” as in
http://www.pickupguide.com/chklgc.htm
But there are some really funny uses to be found through Google.
I said I was talking about local variations. You’d never hear it used in that way here, even though there’d be no ambiguity about what you meant.
Bolding is mine.
If I was on the receiving end of oral sex, but didn’t reciprocate, I’d still say I got laid. Or is that “lade”.
I’d say you got lucky.
I wouldn’t use it that way. Getting a blow job is not getting laid. Not that there’s a hierarchy there, but “laid” is pretty much equivalent to “f*cking,” and back in my day didn’t include BJs.
I understand Clinton’s denial more and more as time passes.
I’m assuming that by non-genital sex the OP means sex in which neither partner’s genetals are directly stimulated, but I could be misunderstanding that. Regardless, that’s the way I intended it, and by extension, I used “genetal sex” to mean intercourse in which one or more partners’ genitals are directly stimulated.