1
general::
Phrase(s): a standing joke
a subject that regularly and over a period of time causes amusement whenever it is mentioned. • Uncle Jim’s driving was a standing joke. He used to drive incredibly slowly. • Their mother’s inability to make a decision was a standing joke in the Smith family all their lives.
McGrawhill's American Idioms And Phrasal Verbs
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general::
Something that is always funny even though it is often repeated. For example, Mary's "Dennis who?" when her husband is mentioned is a standing joke around here. This idiom employs standing in the sense of "established" or "regular," a usage dating from the mid-1500s.
American Heritage Idioms