Also found in: Idioms.
shag·gy-dog story(shăg′ē-dôg′, -dŏg′)
A long, drawn-out anecdote ending with an absurd or anticlimactic punch line.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
a long and involved story, regarded as humorous by the narrator, often told with extraneous detail that culminates in an absurd or irrelevant punch line.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.