My wife brought it up, verbally and then manually the first time we tried it. I don't remember when she first told me she wanted to try it, but it's something she'd always wanted to do. I had a bad experience in the past with someone pulling a surprise unlubed finger-in-the-ass on me, so I was pretty reluctant to try anything but having my asshole tongued. Anyways, one night when I was particularly uninhibited, she slowly worked up to a finger prostate massage, which was pretty amazing.