Throughout the history of sports-entertainment, many partnerships have stuck together through thick and thin to form life-long bonds. From Ric Flair & Arn Anderson to Road Warriors Hawk & Animal to Faarooq & John "Bradshaw" Layfield, no one ever thought they'd see the day where trusted partners would turn against each other.

From 1991-1996, the alliance of Paul Bearer & Undertaker was thought to be in that class as well. But at SummerSlam 1996, the unthinkable happened: Bearer turned on Undertaker, in a moment so genuinely shocking that it checks in at No. 8 on the list of Greatest SummerSlam Moments.

For seven years, Undertaker had dominated WWE, vanquishing every opponent that stood in his way. Right by his side was manager Paul Bearer, who carried the urn that seemed to power The Phenom. But to paraphrase Keanu Reeves from Bill & Ted's Excellent Adventure, strange things were afoot in WWE in August 1996; Mankind, Undertaker's biggest rival to date, seemed to have the Phenom's number to boot. Their tensions boiled to a head at SummerSlam, when the two met in WWE's first-ever Boiler Room Brawl. Its premise was simple: The No Holds Barred Match began in the Boiler Room, and the first man to make his way to the ring and retrieve an urn from Paul Bearer would be declared the winner.

It may be inaccurate to say that both men threw "everything but the kitchen sink" at each other — especially since in all likelihood there was a discarded kitchen sink down in the boiler room. Regardless, the two archrivals brutalized each other, leading to Mankind escaping the boiler room first. The Phenom quickly followed, however, and as both men made their way to the ring, the capacity crowd inside Cleveland's Gund Arena roared with anticipation.

After knocking Mankind off the apron, Undertaker entered the ring and got down on one knee, bowing to Bearer and the urn like he always had. This time, however, Bearer didn't hand the urn to The Phenom; instead, he turned his back, causing our fans in Cleveland -- and most likely those watching in their homes around the world -- to let out a collective gasp.

As Undertaker questioned his career-long manager, Mankind snuck back in and slapped his Mandible Claw on The Phenom. Once Undertaker was out, Bearer fully revealed his shocking turn by laughing maniacally and consorting with Mankind to attack his former protégé. In the ultimate -- and final -- act of betrayal, Bearer smashed Undertaker's skull with the urn before handing it over to Mankind, giving his new ally the victory.

Our fans sat in shocked disbelief as Bearer threw away his six-year bond with Undertaker to cast his lot with Mankind. As several druids came to the ring to take away Undertaker's lifeless form, reality sunk in that his tandem with Paul Bearer was no more, and a new era had begun…one that would plague not only The Phenom, but all mankind.