fake breasts
When a character stuffs an object into their top to pretend to have (bigger) breasts. Unlike breast padding this should be flagrant and not an object designed for the purpose.
Generally not for use with breast implants unless they can somehow be seen beneath the skin or are mentioned by a character in the image, since it's impossible to tell the difference between odd/unrealistic breasts and odd/unrealistic art style.
See also
This tag has been aliased to breast_padding (learn more).