Barnicle Syndrome is a chronic mental illness. Barnicle Syndrome commonly expresses itself in those with low-self confidence. Those with barnicle syndrome need to be at someone's side, 'clinging' to someone, or to be in sexual activity with someone in order to satisfy the gaping hole that their self-confidence lacks.
1: What a slut man... look at her making out with guy after guy
2: Nah dude, she's not a slut, she just has Barnicle Syndrome.