Amazon.com has audio clips of "The Happening" by The Supremes on the albums listed below. To listen to a clip, click on any album name and you will be taken to a CD product web page with a list of album tracks linked to song clips.
20th Century Masters: The Millennium Collection Vol. 2 - Diana Ross & the Supremes - UniversalThe Amazon.com MP3 Store also has a clip of the above song on the album listed below. Click on the album name and you will be taken to a list of mp3 album tracks with audio samples that include the above song.
Anthology  - Diana Ross & the Supremes - Universal (2 CDs)
Diana Ross and the Supremes - The Ultimate Collection - Diana Ross and Supremes - Motown
Forever Diana: Musical Memoirs - Diana Ross - Motown/PGD (4 CDs)
Gold - The Supremes - Motown (2 CDs)
The #1's (Eco-Friendly Packaging) - Diana Ross and The Supremes - Utv Records
The Ultimate Collection: Diana Ross And The Supremes - The SupremesCDUniverse also has a clip of the above song on the album listed below. Click on the album name and you will be taken to a list of albums, including the one below, that include the above song. (Note: Those albums with music note icons all have song clips. To see the entire list of CDs, you may need to scroll down all the way to the bottom as many songs have lyrics and other information displayed at the top.)
Gold - Supremes