I also agree with sniffing undies, i never done it until i hooked up with a buddy of mine. We have been buddys now for 3 yrs, the smell of his body made me wonder how his undies smelt, so one day i grabbed them, oo my god, they smelt great.
Now what i do, is he leaves a pair of his shorts behind, when his man smell is gone, i wash them and the next time he comes over we do the exchange program.