We all know of the standard second base, third base, etc. when describing different kinds of sexual endeavors, but there are many other baseball terms that are used more rarely to describe these kinds of acts. For instance:
Sacrifice Fly: A term describing the act of "taking one for the team". You sacrifice your dignity and get with a below average friend of a girl so that he can score.
First Base Coach: This represents your wingman. Once you get to first, he advises you to either make your way to second or stop at first if he knows you won't make it.
Check Your Swing: This symbolizes being about to get with a girl, but then at the last moment decide that it's not a good idea, and that you'll try your chances when a better girl/pitch comes along.
Fielder's Choice: This term comes into play when 2 guys are both trying to get with the same girl, and you know that she is going to throw one of them out and one is going to reach base.
Foul Ball: This has the simple meaning of being shut down, but in a nice way. You try to put the ball in the field of play to get on any base, but you a turned away and must try again on a different pitch.
Ace: This is a girl that rarely lets any guys get on base. Only if a guy is a really good hitter will he have any chance of getting anywhere with this girl.
Bases Loaded: This is just a full out orgy. You have a guy on first base, second base, and third base all at the same time, all within the same area. If you reach base, you know at least one of them is going to reach home plate.
Strikeout Looking: This term means the girl has given the guy a clear sign she wants him on one of the bases, but he just lets it go by and the opportunity is lost.
Stealing Home: Rape.