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An annual day celebrating labor around the world. There are three major dates for Labor Day: in most countries, Labor Day falls on May 1st (or thereabout), often synonmous with International Workers' Day; in the US, Canada and parts of Australia, it falls on the first Monday in September; and in Japan, it falls on November 23rd, known as Kinrou Kansha no Hi (translated as Labor Thanksgiving Day, born out of the Niiname-sai harvest festival), though many trade unions still celebrate May 1st.
The Homestar Runner quote "Todaybor Day is Labor Day" (from the 2004 Labor Day-themed short "Labor Dabor") gets quoted by older American users online whenever September arrives.
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