adj. Mentally cleansed, espeically of behaviours, attitudes, or even memories considered "undesirable" by one partner. To truly shampoo a partner requires a great deal of effort to achieve the required level of obedience, but results in a docile and obedient lover who cannot conceive of not wanting to obey and please.
GF1: "Damn, Margot really shampooed her toyboy!"
GF2: "He doesn't even recognize his old girlfriends anymore..."
GF1: "She took him from free-range boi to shampooed toy!"
Have you ever noticed, while bathing, that while it takes quite a bit of shampoo to lather your hair up the first go-round, if you try to lather it again a second time, it only take a drop?
Well, being shampooed means that you were drunk the night before and it takes you only one drink to get hammered again.