Anglicized version of "lambón" - a Dominican slang term meaning "one who licks", referring to freeloaders and tagalongs; the lambis is the one who orders an appetizer, only to ask for a bite of your entree later. The lambis also has a habit of inviting themselves to social events where they are not welcome.
Plural: Lambii (not lambises, as is popularly believed)
"John was not invited to the potluck, precisely because he never brings a dish, but always helps himself to generous portions of a wide variety of dishes, as he did today. What a Grade A lambis!"
"Mary, in classic lambis fashion, asked several of her friends for a taste of their confections when they went to Dylan's Candy Bar, having purchased none herself."