Graham Barker of Perth, Western Australia, is a navel fluff enthusiast. Navel fluff, you ask? Yes, it's that lint that accumulates in the belly button, discovered only during moments of deep self-reflection, and often leading to difficult questions like, "Why is it blue?" and "Is this much fluff normal?" and finally "Why am I even thinking about this?" Well, Barker has made a twenty-year hobby of collecting, studying, and cataloguing his fluff, and his navel fluff collection is truly a thing to behold. Here's a picture of his "priceless collection":
And here's just a sample of Barker's discussion on the navel fluff phenomenon:
Those with hairy stomachs tend to generate more fluff, as abdominal hair is alleged to assist with dislodging fibres from clothes then collecting and channelling them into the navel. Also those with larger bellies often experience greater volumes of fluff - possibly due the tendency of large stomachs to possess deeper navels, thus a larger space for the lint to lodge in.
But how does it accumulate in the navel? Dr Donald E. Smith remarks that navels may possess a moist and sticky secretion that catches whatever lands nearby. On the other hand, Dr Bhupendar S. Gupta, whose doctorate is in the study of textile fibres, attributes the accumulation of navel fluff to the stomach's "microclimate" - where the flow of air between clothing and the abdomen carries small lint particles that get lodged in the navel.
Probably the best investigation into navel fluff was conducted by Dr Karl Kruszelnicki of the University of Sydney. He devotes a whole chapter to it in his popular science book "Q&A With Dr K" (Harper Collins Publishers 2001). ...
Seriously, people. Go read all about this. There's a whole world of research and theory involved -- although, admittedly, much of it is generated by Barker himself. See also: Barker's page of classic comments, history of fluff, and his appearance on The Tonight Show. And if that's not enough for you (perhaps you're an "outtie" who cannot collect much fluff), witness Barker's collection of beard trimmings.