Breasts with more supportive tissue (dense breast tissue) are firmer and harder to the touch than are breasts with more fatty tissue (nondense breast tissue). A good balance results in soft, supple, yet firm and perky breasts.

Cancer is harder to detect and more likely to occur in dense breasts.

Sounds weird when used to compliment nice breasts unless referring to perkiness because that would otherwise indicate a hard breast, similar to some augmented breasts.

Background: www.mayoclinic.org

Mercury retrograde is the act of taking a shit whilst mooning one or more human beings. Your day can typically being going well, according to your horoscope, until you are forced into witnessing Mercury retrograde. Performing Mercury retrograde will often speed the astrological cycle forward for the individual performing the Mercury retrograde, bringing about happy and fruitful times to come.

Like bags of sand. Often mistaken for implants, even on close inspection. The bane of mamographers everywhere.

This is what Google translate comes up with for the British insult of calling someone a "thick tit"

Excessively full and firm breasts

A breast that is firm, not flappy, holds its own.

Breasts that are hard and not soft and squishy. Having dense breasts means that you have an increased chance of getting breast cancer.