Jesus' Son is a collection of short stories which are linked by common characters. They take place in Iowa or there'a'bouts, in the '70s as far as I can tell. The only other book I've read by Dennis Johnson is his Vietnam epic Tree of Smoke, which was a heck of a lot longer. Jesus' Son is basically a concentrated dose of what he seems to do best: show messed up people doing messed up things, using spare/raw language with flashes of religious imagery now and then. The characters have a fuckall attitude and are very much in the moment. This is the sort of down-and-out-full-blooded life, sans sophisticated self-consciousness, that American poets have been writing about since Whitman.
It's also damn funny. Especially the story called "Emergency".
The title comes from Lou Reed's song, "Heroine":
--When I'm rushing on my run.
And I feel just like Jesus' son...