Home Game: Lynn: So how’d it go with Bob last night? Everything was going fine and then, just when it mattered most: Casey at the bat…
Ok, actually, we do still use baseball metaphors, more often that you’d think. Using the great game of baseball, with all its adrenaline and expectations and excitement and strike-outs and and, uhm, balls, as a way to express our sexual endeavors is ingrained in the psyche of every young kid who grew up under the red, white and blue.
Let’s leave blatant sex talk to the French, shall we? (Note: Probably the least celebrated and referred-to base ever.) Third Base: Fondling…with your mouth. Fifth Base: How to put this delicately…the, uh, final frontier.
To use the expression correctly, you get or make it to a base, per my comment: quotation, if I interpret it correctly, they had intravaginal sex twice and then she performed oral sex on him.
If we say home base = fourth base, that's 4 4 − 3 = 5, the subtraction because he was receiving instead of giving.
"I got to second base with that girl yesterday." "I didn't think I had a chance, but I made it to third base with her last night." One of the other answers has provided a nice link to the Wikipedia entry for baseball metaphors for sex.