They don't, because it comes open instead.

*Knock* *Kno- *creaaak*

The door in front of you just came open on the second knock. Your neighbors don't notice as you stand in their doorway watching, momentarily mesmerized by how sexy they are. The pale redhead is on her hands and knees getting the pipe laid into her by a fit young man.

"Hey could you keep it down, it's almost 1:00 in the morning."

Your neighbors just keep fucking, still seemingly oblivious to your presence in their door. Maybe they couldn't hear you over all her moaning and cursing.

You repeat yourself, and again they don't respond to you, so you walk towards them. You aren't even aware that your hand is in your pants and you're playing with yourself to their inadvertent show.

As you get closer, the man looks up, so you repeat yourself. This time he responds with a noncommittal "Yeah, sure bro", but makes no effort to stop his pounding. By this point you are aware that your dick is out and rock hard, but things are so odd it doesn't seem out of place.

You move to try to get his attention again when you shudder at the feel of your cock brushing up against something. Looking down, you realize you just rubbed your cock on the woman's elbow, but curiously, neither of them seem to mind. In fact she actually reacts by moaning a little louder, grabbing your dick, and starting to jack you off!

The man looks down and sees his partner with her hand rubbing your penis.

SHIT

You're about to get your ass kicked. You aren't out of shape, but you're not exactly in shape either, and this guy is. It doesn't help that you don't have many fights under your belt in life.

Then he looks up at you, smiling. He takes his hand off the fat ass he was previously kneading. You close your eyes instinctively for the blow you're sure to receive.

"Hell yeah bro, you take that end and we'll spitroast my wife. Don't go easy on her, she loves when I fuck her throat.". You open your eyes and see the mans fist, expectant. Bewildered, you raise your fist to his and give it a bump. You then climb onto their bed. The wife looks up at you with a smile, before lowering her lips down around your cock.