n.s.v.i.p
A person who's all talk and no action
My dad is an n. s. v. i. p. He says he'll fix the roof but forgets to bring the tools.
My friend is an n. s. v. i. p. He says he'll come to the party but never shows up.
My teacher is an n. s. v. i. p. She says she'll give us a test but it's always on Friday.