don't encourage him.
if, his post is the truth.. he's routinely initiating a sexual act on his wife while she is unconscious, a sex act she's expressed reluctance/distaste for while conscious.
she doesn't believe him when he share with her tales of their nightly anal-friskiness.. she has no recall of taking part in any sexual act.
seriously, do you just read the words anal sex and start spouting about prep and lube?