This is going to be a little awkward. :3 Well, when two people are sexually intimate with each other, they share bodily fluids with each other. For example, saliva while kissing, or other bodily fluids while having intercourse. This is what is meant in this dialogue. If you dance with someone, especially in a romantic setting, you might end up kissing them. And that can lead to 'shared bodily fluids'. In this example, this is an undesirable thing to the speaker so they are using it as an excuse to not dance.

Lol. Yes it's a delicate and humorous was of saying sex.

In this context I believe its just another way to say have sex. Sharing bodily fluids=having sex. Pretty sure this is the context.