Just a peek

Deciding to sneak a peak you creep toward her door and try peer in and steal a glance. With the lights on in her room you can see the foot of her bed bouncing as you approach. When you peek in you are shocked to see your sister bouncing on top of an older man who appears to be in his forties. "Wait a minute that's Mr. Williams mama's boss!" you scream in your head. You watch as your sister rides him like her life depended on it. Her pert C-cup breasts bouncing up and down as she slams her hips down on to his. You stare mesmerized as her moans echo throughout the house and in your head. Mr. Williams takes her left breast in his hand squeezes and plays with it and sucks on her right nipple at the same time. Your sister just squeals while she grinds on his cock. Alejandra holds herself above him slightly and Mr. Williams starts to piston his cock in and out of her eliciting a groan from her, as she starts to rub her clit. "Oooooh my gooood YES! Papi give it to me I'm cumming!" she cries out as her legs begin to shake. "Me too" is all Mr. Williams says as he slams his cock into her. You watch as both of shudder simultaneously and your sister collapses on top of Mr. Williams. You watch in astonishment as the two lie there panting, and just as you're about to leave Mr. Williams looks over to the door and locks eyes with you causing you to freeze in horror. He gives you a wink and slaps your sisters ass causing her to giggle and snuggle up to him. Deciding not to tempt fate anymore you head back into your room to hide. You didn't realize it until now, but your cock is painfully erect and you feel incredibly aroused after what you just saw.