Boyfriend Slaps My Wet Ass in the Shower

She knows exactly what she're doing to you. Her wet ass is right there, the water streaming down her back, and all you can think about is touching it, slapping it like her boyfriend is. He grips her hair, pulling her forward, and you can see how much she loves it. Her back arches, her arms bracing against the wall as his other hand comes into view.

His hand starts slapping her buttocks rhythmically, the sound echoing off the tile. You can't help but imagine how that feels, how wet and warm her skin must be under his palm. She doesn't move much, just shifts slightly with each slap, her hips swaying. You're getting harder by the second, your pulse racing as you stroke yourself. How long will you last?

You're edging already, your breath catching in your throat as you think about being right there with them. The water keeps flowing down her back, pooling around her feet as she stays bent forward. His hand rests lightly on her left buttock at the end, the water still streaming steadily. What happens next?