Southern’s letters were antic, but they were also surprisingly unlettered and juvenile in an ur-Judd Apatow sort of way. (A lot of penis jokes.) He was not a close observer of people, in these letters, nor of his environments. He didn’t reveal much about his own life. There aren’t many facts to hang onto.
...[A]s a correspondent Southern was not, generally, all that preoccupied with things that were going on his life or his career. In writing to friends, he tended to be motivated by an almost helpless impulse to amuse, shock, titillate, and appall. The vast majority of these letters were written to male friends, and a great deal of creative energy went into conjuring absurd and often incredibly misogynistic sexual scenarios involving female acquaintances.