Young girl masturbates when she hears her stepsister her boyfriend on the bed under her bunk bed!

A shy, family-friendly half-sister, who has never dated, and who wakes up early to work every day. When she and the other older woman are home alone at night, they often watch TV together! But when she finds out that her stepsister's boyfriend is coming to spend the night at their house, she worries about going to her room to go to bed early. But, in fact, she waits for them to lie down on the bed under the bunk so she can listen to all the fucking that happened between the two.