Weed. I was married to my wife for 17 years. One night over Thanksgiving at her mom's house after everyone else had left and her mom had gone to bed, her brother asked if we wanted to go out and smoke. My wife smoked in HS and college, but I never had. She gave me the "do you want to" look and I agreed and out we went. I got high for the first time at 45. She had always told me weed made her horny and OMG had I known just how horny I would have gotten some many years before. The sex that night was incredible even though we couldn't go crazy with others in the house.
But I got some to take home and when our kids were gone at sleepovers on night we got stoned and went crazy. All of a sudden she clenched and got very very wet. Her first squirt. Can only do it on weed as we have tried other times and she just can't. Don't really know why.