I was on a date with my new girlfriend at my place when my old friend suddenly showed up. I accidentally spilled wine on my chest, and while she wiped it off with a towel, my nipples rubbed against it and caused an unexpected creampie inside my pants! Thinking I'd be mocked, she instead teased my nipples, training my sensitive pussy to become more resilient. She even helped me practice sex, using nipple play to further strengthen my weak dick. My old friend has always been a caring older sister type, but I never expected her to be this considerate. I borrowed her chest, got creampied multiple times, and trained my nipples until I became a real man.