The gradual yet unstoppable process by which your wife or girlfriend's clothes take over your wardrobe. It often begins by the male partner naiively agreeing that he will temporarily host a single garment because of a short term capacity issue in the female wardrobe. From this point on the male no longer has control of his wardrobe.
Becky: Darling, I'm just putting my long dress from Kirsty's wedding in your wardrobe - I've run out of hangers in mine. Is that ok?
Chris: Of course, go ahead
(Six months later, and the effects of wardrobe creep are clear)
Chris: Why is my wardrobe full yet I only own two items in it?