I had one recently of smearing yogurt over someone's nude body while they splashed more on mine until we were both painted and dripping in tangy white goodness. There weren't even any sex acts other than both of us getting really aroused from the yogurt slowly encroaching over the empty canvas of our naked flesh.
I had one somewhat recently after discussing with a close gal pal of mine the idea of re-creating the scene from Batman The Animated Series where Harley comes of a pie to sing to Joker. The conversation somehow turned to her admitting that she has always wanted to do something like that and offering to have me and/or wife photograph this for a private collection or to be used on her social media at her discretion, but never to be shared without permission. That turned to a whole idea of what would happen if we dressed her up like Harley, dress my wife as Batgirl and possibly have me dress as Joker and we pie the hell out of each other while recording video and the occasional photos of the whole thing. Again, this is merely a dream and not likely to happen or be shared if it ever does.