The magic of sildenofil (5-[2-ethoxy-5- (4-methylpiperazin-1- ylsulfonyl) phenyl]-1- methyl-3-propyl-1,6-dihydro-7H-pyrazolo [4,3-d] pyrimidin-7-one) better known as its citrate salt, Viagra, revealed itself today as an aside discussion about nitrous oxide.
Seems it interferes with an enzyme called phosphodiesterase-5 located in the smooth muscle of the arteries that supply blood to the penis. This action prolongs the action of nitrous oxide to trigger the relaxation of the smooth muscle that lines the arteries and cause erection to stay longer than usual. Prolonged erection can be dangerous however.
If the light stays on for more than 4 hours, please call the electrician.
Let us not look back in anger or forward in fear, but around in awareness. 
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