Johnny-come-lately

He's a johnny-come-lately.

She might take offense if some Johnny-come-lately thinks he can do a better job.

Morris now shared financial decisions with a woman, a female Johnny-come-lately. Imagine the eventuality of Morris's share of their fortune ever falling into such Johnny-come-lately hands. God forbid!

In a field increasingly populated with Johnnies-come-lately, Gittings is a Johnny-come-early: one only has to read this book to feel the depth and span of his knowledge.

The government should give the agency its independence back so that it can get on with the task of protecting consumers in relation to food without political interference from johnny-come-lately ministers.

All these Johnny-come-latelies typically come out as irreverent, vulgar or immature and childlike.