Well alcohol is a vasoconstrictor which means it constricts the blood vessels - not the kind of thing a guys needs right before sex as you want more blood flowing down there not less, on the other hand caffeine is a vasodialator which has the opposite effect. I learned years ago never to drink alcohol when there's a chance that evening I might be with someone, I go for an energy drink instead. But as far as condoms go, yeah I've not been able to get off with one on for years, just don't get the sensation needed to, I just go for the hand job at the end once she's satisfied.