A diease caught from smoking weed which causes your nipples to change to various colors, most commonly yellow, and also causes them to dry up and in some cases even uncontrollable milk spurtage. In very rare cases your nipple may bleed an/or grow upto 10 feet long.
(John enters doctors office)
John: doctor my nipples are changing colors
Doctor: Have you been smoking weed lately?
John: Yes i did just yesterday
Doctor: Well sir, you have yellow nipple diease
John: I should have seen this coming
Doctor: Ha, you said cum.