Keep your mouth shut and get to work!

You quickly run through your options, your mind racing as your brother's confusion grows. You could try to explain, but that would just lead to more questions and potential ruin of your plan. Also it would be awkward as hell. So, you consider other options.

Could I just blow him? That might shut him up for a bit. You think, imagining the look on his face if you were to suddenly drop to your knees. But then again, he'd probably wonder why I'm so eager all of a sudden, and my voice would give me away as soon as I start talking dirty.

You picture yourself on your knees, your brother's eyes wide with surprise and arousal. You'd have to keep your mouth shut and just get to work, but that wouldn't solve the problem of your voice.

Fuck it, you think, I'll just have to deal with the voice later. Right now, I need to keep him from asking too many questions.

You decide that a blowjob is the best course of action to distract him and buy yourself some time. You turn around to face him, a playful smirk on your face, and push him gently onto the bed. He looks at you, still confused but clearly aroused.

"Babe, what are you—?" he starts to ask, but you cut him off by dropping to your knees in front of him.

You quickly unbuckle his belt and pull down his pants, his hard cock springing free. You take a moment to appreciate the view, your sister-in-law's body responding with a rush of excitement. You lean in and take him into your mouth, your gruff voice temporarily forgotten as you focus on pleasing him.

Your brother lets out a moan of pleasure, his hands tangling in your hair as you bob your head up and down. You can feel his cock hitting the back of your throat, the sensation foreign yet exciting. You use your tongue to tease the sensitive underside, your hands gripping his hips to keep him in place.

"Fuck, babe," he groans, his voice hoarse with desire. "That feels so good."

You continue to work him over, your mind racing with the need to keep him distracted. You can feel his cock throbbing in your mouth, his body tensing as he gets closer to the edge.