The Sexual Adventures of Sherlock Holmesby Larry Townsend, a.k.a. J. Watson
The Sexual Adventures of Sherlock Homes (TSASH) is a novel released in both hardback and paperback. Earlier editions list the author as J. Watson, a pseudonym of Larry Townsend who is credited as the author in later editions.
This book is clearly in the genre of erotica and predominantly relates to sex acts. However this is fairly well written erotica and set within a reinterpreted canon that I, for one, found rather entertaining. Christopher Redmond, author of the Sherlock Holmes Handbook, who described TSASH as a novel "that betrays a deep and sensitive knowledge of the Canon" (pg. 254)
The Olympia Press paperback edition (The Other Traveller imprint) was released in 1971 under the pseudonym "J Watson". This edition has no page number or ISBN.
The "Badboy" paperback edition of the Sexual Adventures of Sherlock Holmes (left) was released in 1993. Most, if not all, copies of this edition suffer from a badly trimmed cover missing part of the title and author's name on the far right. For this reason TSASH is sometimes listed as being authored by "Larry Townsen". This edition is 258 pages, ISBN 9781563330971.