There comes a state of being wehre it's possible to laugh even at terrible things that have happened. Look at the film "Life is beautiful" (which I hated, actually). I certainly have laughed at dark things in my life at times, and I guess your friend was there with respect to her rape experience. However, throwing it around on social media is insensitive, stupid/ignorant. Some things are meant to be shared in private, or at least a more appropriate context.