A fetish involves around turning a character (particularly female) into a "bimbo", i.e. being an often airheaded, hypersexual version of themselves.
Typically, bimbofication involves drawing character with exaggerated makeup and sexual characteristics, such as giving them larger breasts or hips. The character's personality is often changed to being fixated on sexual pleasure to various degrees (some retaining their original personality but with more libido, while some are depicted as a stereotypical carefree adulterer).
Usually, bimbofication often stylized the character into a gyaru and/or ganguro state of dress in Japanese fetish art, though others may simply give them sexually provocative revealing clothes and often depicted them as prostitutes.