Quickly jerk off, sniffing your dad's underwear.
From Create Your Own Story
You decide to jerk off while continuing to watch your dad in the shower.
You quickly but quietly reach over and pick up his boxer briefs. You cover your nose with the crotch and inhale deeply, taking in the scent of your dad's groin. Your cock aches for him, and you slowly lean back over to get another look.
He's still facing away from you, and though you've never tried it before, your dad's ass looks good enough to eat. Although, you'd always imagined he'd be the one doing that to you. His hot-headed ways always cast him as the aggressive type in your sex dreams about him.
You pull your dick out, a thin string of pre-cum creating a line from your boxers to the tip of your prick. You use a thumb to swipe it off of your cock-head and put the thumb in your mouth, licking your own sweetness off of it, but wishing it was your father's. You begin jerking, continuing to breathe every ounce of your dad into your lungs as you do it.
Suddenly, you hear movement from the other side of the curtain. Fear stops you mid-jerk, and you're suddenly frozen in the moment for five or so seconds, your heart attempting to beat itself out of your chest. Finally you get up the courage to peek back in.
Your dad has finally turned around, facing you. His eyes are closed, and he is roughly rubbing shampoo into his hair. A light dusting of dark brown chest hair covers his pecs, travels down his stomach, and trails off, ending at his pubes which are trimmed short allowing a full view of his penis.
His cock is magnificent. It was two or more inches bigger than yours was and almost as thick as a can of soda... and it seemed, from what you could tell, soft. Your dad's dick had to be fucking massive. If only you could kneel before it to worship it properly with your mouth, or, better yet, bend over on all fours to let him aggressively fuck your tight, little asshole until he came.
You pull your head back away from the shower, the image of his massive member burned in your brain. You inhale another deep breath, and you exhale, your breath coming out in gasps. Your hand is furiously jacking, and you can feel an orgasm approaching. You move the boxers down to your mouth, push them inside, and bite down as your cock pulses three, four, five times. Thick streams criss-cross across the front of your shirt. A bit hits the bottom of your chin. You smile, removing the underwear and tossing them back to the pile of your father's clothes.
More movement from the other side of the shower forces you quickly to your feet and quietly through the other side of the door. Your whole body is shaking from one of the best orgasms you've ever had, you're covered in your own spunk, and your heart is beating faster than it ever has in your life. You hurriedly escape back to your room, use the bottom of the cum-stained shirt to wipe your chin, and peel it off yourself, so you don't get cum everywhere. You quickly toss it, still inside-out, into a corner of your room.
You then, pull out and put on another shirt. You steal a glance in the mirror, checking to make sure the cum is gone and that you look somewhat presentable. As you exit your room and head for the front door, you hear the old pipes of the cabin screech to a halt and realize your dad is finally getting out of the shower. Being that you just spied on him naked and practically ingested his undies while you came, you figure it's probably best you should head outside.