The siblings, their bodies pressed tightly together in the confined space, can barely contain their excitement. The boy's cock, rock hard and leaking pre-cum, is inches away from his sister's eager mouth. She leans in, her breath hot on his skin, and takes him deep into her throat. He groans, his hips bucking as she sucks him with increasing fervor. She pulls back, her lips glistening, and jerks him off, her hand moving in sync with his thrusts. He feels his orgasm building, and with a final thrust, he comes, his cum spilling out in a hot, sticky mess, coating his sister's hand and dripping onto her hungry pussy.