As you distract your friends with random small talk, you don't realize that the flashlight's switch caught on the edge of your jeans as it slid into your pocket. The pink light flicks on, but is at first simply absorbed by the material of the pocket itself...except in one place.
A small hole on the inner liner of your pocket has been growing for months, and already you've lost a couple of pens to it. Had you realized something more important was going to be at stake, you might have gotten it repaired or at least bought new jeans. Now, however, it's too late; the flashlight has twisted sideways and now pokes through the hole to shine its pink light at your crotch. At first the material of your boxers, like your pocket, absorbs the light. Unlike your pocket, however, the boxers are distinctly masculine and begin to change into their feminine counterpart: panties. The change is slow with the dim pink light, but you're absorbed in your conversation with your friends so you don't notice. Even more importantly, the fabric of the pocket is keeping you just separated enough from the flashlight that you aren't aware of any changes.
Even when you finally go sit by the fire to continue chatting with your friends, the movement only serves to press the flashlight against the hole in your pocket. Having fully transformed your boxers into silky panties (which you remember putting on that morning, if you care to think about it), it now goes to work on what's underneath. Your cock, previously tight against the fabric of the panties, begins to shrink. You shift in your chair, not feeling as the rod dwindles down and tucks itself in the top of a newly-opened slit in your crotch. The edges of the slit roll back into the folds which will become the lips of your new vagina. Meanwhile your balls have also shrunk, and one by one slip through those folds and into the womb growing inside your body. As they travel upward, they have already morphed into ovaries, and they take their rightful place at the top of your new reproductive system.