Trout pout is a British slang term for over-sized lips, usually on women, due to collagen implants. The term first rose to prominence when the actress Leslie Ash underwent collagen injections on her lips. The procedure went horribly wrong, leaving the star with over-sized, swollen lips. The reference to trout comes from the large lips on most dead fish.
Leslie Ash's lips were a major news item in British tabloid papers in 2003. Viewer ratings for her BBC1 show "Cops" rose substantially when viewers tuned in to see her trout pout look.
The term trout pout has now passed into the British language as an expression for a woman who has over-sized or enlarged lips, especially after implants.
