Masturbation. Exclusively masturbation of men or boys, since "log" is another word for penis.
Phone sex convo between two gay male politicians:
Gay Politician 1: Maybe later we can go back to my place and I can take your census.
Gay Politician 2: Only if you'll filibuster.
Gay Politician 1: Reapportion me, baby
Gay Politician 2: Oh I'll do it, you carpetbagger.
Gay Politician 1: Porkbarrel me!
Gay Politician 1: There's some logrolling going on... IN MY PANTS.
Gay Politician 2: You want PROPORTIONAL REPRESENTATION?
Gay Politician 1: I think I have a majority of your ass.
Gay Politician 2: Oh man, I think I just lost my seat.
Gay Politician 1: I'm about to incumbent!
Gay Politician 2: Errg. Oh YEAH! This session of congress is now over.
Gay Politician 1: Care to adjourn, then?
Gay Politician 2: I just did.
Gay Politician 1: Can we call a special session?
Gay Politician 2: As long as you give me your soft money.
The practice of defecating a large sturdy floater, admiring said poopsicle and urinating on it. A well aimed healthy stream of urine causes the "log" to roll.
"Hey, Moonshine Jimmy!"
"Whats happening, Prune Juice Doyle?"
"You sure were in the outhouse for quite a spell, eh?"
"Yep. Squeaky George let out a 13 inch floater and we were having a hell of a time logrolling!"
When a reviewer or critic who gets into a tradeoff of critical praise or "You scratch my back, I'll scratch yours" situation. Implicitly or by agreement, one reviewer exchanges praise (often fatuous) with another in the hopes his inflated regard will find its way into publicity, advertising copy, book-jacket blurbs and the like and increase the other's visibility (and sell more books). The favor is expected to be returned, and at some point is. Probably descended from the literal use of logrolling as a pioneer sport, in which neither participant can stay on the round, floating timber unless one is pedaling frantically one way, one the other, although the symbolism invoking a mutual-gratification pact analogous to masturbation cannot be denied.
In the 1980s, SPY magazine ran a regular column called "Logrolling In Our Time" giving exact instances of such tit for tat.
-- "Oh, God. This is logrolling at its worst. A___ says on the dust jacket of B____'s new novel that 'a new American voice is born.' Three months later B____, now bestselling author, says that A____'s latest textbook is 'unchallengeable in its supremacy in this field.'"
-- "They belong to a mutual admiration society, intellectually speaking."
-- "I'm sorry; did you say "intellectual mastur---"