Chicken Fillet Meaning

(slang) A piece of rubber or silicone placed in a woman's bra under the breast to increase apparent size and/or create more cleavage.

Example: Used other than as an idiom: A piece of chicken breast meat.
2009, Chrissie Manby, Crazy in Love
  […] to wear a bikini this year, to enjoy the season without fearing that my chicken fillets are going to fall out every time I jump in a pool.