happy camper - Phrases/Idioms
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
A satisfied participant, a contented person, as in She loved the challenge of her new job; she was one happy camper. This expression is also often put in the negative, as in She hated the heat and humidity of the southern summer; she was not a happy camper. [Slang; mid-1900s]