When I was 12 I went on holiday with my parents to Spain. On the beach, I got to playing with a young Spanisg girl, probably a year younger than me. We were fooling around at the edge of the water, and eventually we ended up breathless, my sitting in the water, her kneeling astride me.
Suddenly I felt a warmth flowing round my loins... I looked down and saw clear liquid bubbling through her panties... She was peeing on me! She laughed, but I found it a turn-on.