#4 Dean Ambrose's tasteless shots at Roman Reigns
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After Roman Reigns left WWE to fight leukemia last year, WWE turned Dean Ambrose heel and a feud kicked off between former Shield members Ambrose and Seth Rollins. The Architect was the babyface this time, contrary to their feud from 2014, when he had betrayed The Shield.
One promo on an episode of Raw saw Ambrose lashing out at Reigns, and stating that "he'd have to answer to his maker for all of his past misdeeds as a member of the Shield."
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The promo didn't sit well with the WWE Universe and resulted in massive fan outrage. This forced WWE to tweak Ambrose' character in a hurry, which led to him getting immunized in a doctor's office, and coming out to the ring wearing gas masks. The character only turned worse from that point.