Did Doc and John have sex?
They have a homoerotic wrestle, then in the morning John wakes doing up his trouses and Doc rises in only a singlet. This would add another dimension to his fall.
shareDiscussed here:
http://www.imdb.com/title/tt0067541/board/flat/166449080
Yes, it's implied they did the 'Hershey Highway', and that is why John went back with the intention of shooting the Doc.