From Wiktionary, the free dictionary
From rack (“breasts”) + -ne.
rackne (uncountable)
- (informal) Acne on the breasts.
- Synonym: boobne
2008, Marisa C. Weiss, Isabel Friedman, Taking Care of Your "Girls": A Breast Health Guide for Girls, Teens, and In-Betweens, New York, N.Y.: Three Rivers Press, →ISBN, page 63:Yeast infections are different from acne (or "rackne").