Great Thread.
Funnily enough, some time ago now, I remember an occassion when I was lying in bed alone and admiring/playing with my dick, when something else aroused me further.... I can't say if it was a smell, but I guess that it could have been my own male pheromones or the slight smell of my own pre-cum ? It sent me to a level of self arousal I've rarely been too. My whole body became sensitised, my dick actually got bigger still, so much so I couldn't get my mouth around it. It was fantastic. How I wish I'd had the presence of mind to measure it that day ..!