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We've seen a few surprising celebrity relatives in our time (who knew that Dolly Parton was Miley Cyrus's godmother? We sure didn't) but Brooklyn Nine-Nine has well and truly left us shaken with this (fictional) family bombshell.
In a criminally overlooked reference in the sixth series of the cop comedy, Detective Charles Boyle (played by Joe Lo Truglio) said: "My cousin, Susan, didn't know she could sing until her late forties..."
While a few people picked up the reference to the singing sensation who stormed to global fame following her Britain's Got Talent debut in 2009, most fans of Brooklyn Nine-Nine seemingly let the reference fly way over their heads...
...That is, until someone uploaded the still image, and the quote, to the show's popular sub-reddit page.
"Oh, my God," wrote one fan in response. "I just got it."
"It went over my head until right now," said another, once he'd teased out the meaning.
"Yeah I never put two and two together," agreed a third. "None of my cousins have the same last name as me, so I never assumed cousin Susan would be Susan Boyle."
A fourth fan said: "I thought this was so clever when I watched it."
Unlike her so-called cousin Charles, Susan Boyle has naturally gone on to be a global superstar.
While she may have lost out to Diversity during the third season of Britain's Got Talent, the 59-year-old has gone on to release eight studio albums, and has scooped a number of awards for her singing.
Now all we need to do is convince SuBo to appear in a cameo...
Die-hard Brooklyn Nine-Nine fans will have picked up that this is not the first time the show has made reference to famous (or infamous) cousins of the show's characters.
Debbie Fogle, who is played by Vanessa Bayer, has previously mentioned her cousin Jared Fogle - who is known to American audiences as a former spokesperson and the face of sandwich chain Subway.
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