The result of an accepted mating call, also known as coitus or intercourse. This PG version, however, alerts the third party of what's going on without the vivid imagery (aka self-induced porn).
Brenna: What are Baby and Johnny Castle doing in his cabin?
Phil: Don't worry about it -- they're just schpradunkadunking
Brenna: Is that the same thing as "dirty dancing
Phil: It is if you say it is