Lana sex is the reverse of anal sex. This is where you pince a loaf in the womans vagina, then have sex with her.
Dick: Hello Fanny, do you fancy some lana sex?
Fanny: I sure do Dick!
Dick: (removes trousers and crimps one out).
Fanny: Ooh Dick that feels so good, it's like you are doing bad things to my bottom, without the pain!