"Saggy boobs" refers to breasts that have lost their firmness and have started to droop or hang down, often due to aging or changes in the skin and tissues. Full definition
Saggy Boobs aims to dispel many of the myths surrounding breastfeeding, including, of course, the eponymous myth of the title, which it addresses by explaining that breast shape, size, and looks are altered by pregnancy and age, not breastfeeding. (breastfeedingtoday-llli.org)
And most of all, I'm sorry that you went from being two boyant, glorious orbs to the deflated, sad rock - stuffed saggy boobs you are today. (whattheflicka.com)