Back room talk about having sex, about getting sex.
Used to describe one's finding of another, for sexual intercourse.
Does not always refer to full penetrative sex, but simply that a person had found another to have some form of sex.
Also used to signal that they managed to reach the ultimate, that they got what they were looking for, which equates the meaning with gaining success, which generally involves penetrative sex.
Noteworthy: Generally associated with a first time engagement of a person, in that it was their first time together, having penetrative sex.