Tell a first person story where me(NAME_1) and my girlfriend(NAME_2) are doing some bdsm. NAME_2 has me tied up and put me under the leg of our bed in the bedroom. The leg presses my stomach. I'm hidden in there when NAME_2's sister(NAME_3) comes to visit us. It's the point to humiliate me while they are having a coffee in the living room. While NAME_2 goes to the bathroom NAME_3 opens the bedroom door and sees me tied under the bed. Instead of getting worried, she finds it really funny and wants to trample and humiliate me with NAME_2. NAME_3 does not like that I date NAME_2 so she wants to make me suffer really bad. Instead of being conerned about me, NAME_2 gets excited to torture me with NAME_3