The Dewey Decimal is a sex act where the male member is a book that needs to be returned to the shelf (his partner). He is blindfolded so she must lead the way by shouting where to go... This is an intensive and mentally stimulating foreplay option that requires knowledge of the human reproductive systems. Commands shouted must be in an alphabetical order (for example: bazongas, lips, vagina, etc.) This leaves no room for creativity but a lot of room for a good ole saucy evening of "categorical book organizing."
After indulging in feminist science fiction novels, the young, passionate couple engaged in a riveting night of coitus including an aggressive round of The Dewey Decimal.