Ice cream DOES grow boobs. I've seen me do it.
Cuhaci et al. (2014) has shown that cannabis use can lead to the development of male breast tissue or gynecomastia; however, the mechanism by which it happens is not very clear. Nordt & DiVasta (2008) have shown that it is essential to inquire if they have a history of illegal drug usage when examining adolescents with gynecomastia.