I take it back...after giving this some more thought, definitely Obsession for Men by Calvin Klein. I know it's seen as a mature man's fragrance (I'm 27 and I'm definitely not mature in at least two different ways

...but, it's the 1st and only fragrance that taught me that it's possible to actually fall in love with and yearn for a scent. I had sampled many fragrances before and though, yeah some were good, and others were better, once I took a sniff of Obsession, it instantly gripped me and had me thinking about not much else besides its amazing smell for days. Not a lot of frags do that for me, infact, this is the only one that has! There are many fragrances I like, but i'd say this is the one that started the ('scuse the pun) obsession...