I never expected to get an erection just from my sister's naked body (huge breasts)! During a long-awaited family hot spring trip, I was surprised to find my sister's breasts were unexpectedly large, causing my penis to become so hard it was almost painful… 4 HUNT-847

I went on a family trip with my older sister to an open-air hot spring. I hadn't noticed before, but my sister had huge breasts, and I unexpectedly got an erection. As she leaned closer, caught off guard, I was thinking, "Oh no!" when she noticed and reached for my penis…