Slap, slap, slap!

Why do I have to get to the point where I'm making that, slap, slap noise while I'm beating off in order to get off? Is it normal to work so hard in order to cum? It's the same even if my wife is giving me a hand job, or I'm alone watching porn. Why does that slapping noise excite me so? Come on, most of you guys out there beat off. Is it normal for you to have to slap, slap, slap one off, too?