It creates the perfect amount of friction. I find that if I use soap, it is too slippery and I squeeze too hard.
Baby oil is good at the beach but it is messy to clean up at home.
And she is so wet that its dripping off your chin. Take that love juice and beat off with it right in front of her. Its great to shoot it on her tummy. The next best thing is mayonnaise, Kraft mayo light seems best. Use water-based hair gel, the type that is slippery not sticky.