Dogs may lick humans’ armpits for several reasons. Dogs have a keen sense of smell, and the armpit area contains scent glands that produce unique odors. Licking the armpits could be their way of exploring and gathering information about you. Additionally, dogs may lick armpits as a sign of affection or to seek attention. However, if excessive licking or discomfort is present, it’s essential to monitor the behavior and consult with a professional if necessary.