A Couch Mango is a project team member, located in a tropical locale, who has indeterminate skill, role or authority, but who fits in seamlessly with the locals and can tell you all the gossip within a week or two.
Often Couch Mangoes will become local legends, with individual acts of random altruism or demonstration of skill being retold in unlikely places, creating yet greater mystique and an aura of untapped capability.
Whilst the Couch Mangoes themselves prefer a low profile and just quietly help the project along, trusted colleagues tend to talk up these unusual incidents to all and sundry.
Do you know Bert? He has has only been up here in Townsville a week or two. I wasn't even sure of his name, but the taxi driver this morning told me that he's very skilled, and is helping him find a better job. I think he might be a right Couch Mango. Let's invite him out for a drink after work - he'll know where to get a good feed.