One of my favorite webcomics, Girls With Slingshots, recently had a very entertaining strip . I think it highlights the importance of establishing common definitions when talking about sex. In many cases, colloquial terminology about sex is intentionally vague because people are uncomfortable talking about it. This can unfortunately cause a lot of misunderstandings and leave all members of the conversation confused about what actually happened.
I completely agree with the idea that baseball is a really confusing metaphor for sex. People generally agree on what the terminology means but not in all cases. There’s a lovely article over on Scarleteen entitled To Slide or To Slice: Finding a Positive Sexual Metaphor that discusses several other problems with the baseball metaphor and suggests the delightful alternative of using pizza as a metaphor instead. I think that it works pretty well. There are lots of ways to enjoy a pizza and not everyone likes toppings. For that matter, not everyone likes pizza. You probably wouldn’t just order a pizza with someone without talking about it first, and if it turns out that you don’t like the same toppings then you don’t get pizza together in the future, you order something else.
However, as much as I do like the metaphor, I do see some trouble with using it in conversation. Because of the variety of toppings and ways to eat a pizza it would become even more difficult to understand what people are talking about. A pepperoni and pineapple pizza could mean very different things to different people. I feel like it might just be easier if people felt more comfortable saying what they actually meant. It would certainly cut down on the confusion.