He was fascinated by the question: Why do some belly buttons collect more lint than others? But no one knew the answer. So for three years he collected his own belly-button lint to find out.

Over the next three years he collected 503 pieces of lint, weighing almost a gram in total. At one point he shaved his navel. He asked male friends, colleagues and family members about their own ...

Perhaps these people with very small amounts of belly hair wore tight clothes, which helped carry the lint towards the belly button. Once it fell into the belly button, it wouldn't easily come out ...

Doug suffered from/enjoyed BBL. He thought that the hair on his belly was "channelling and concentrating lint from his clothes into his belly button". So he decided to test this theory.

Sometimes, an expanding belly can turn a pregnant woman's innie into an outie.