1. Holding tight and not letting go, even if attempts are made to dislodge. An excessively clingy person with irritating tendencies who latches on to people (that usually are unwanting of the attention) is said to barnacalize people.
2. A very tight hug, moreso than a glomp
and always an unwanted thing. Can be used more generally as a derogatory way to say hug.
Source: "...he'd never been hugged by anyone before. Sure, he'd been barnacalized by Relena (a mighty disturbing experience), but a real hug was different."