Having Justin Bieber serenade you while strumming a guitar naked might be every little Bieber fan’s dream, but we highly doubt that fan includes his grandma.

During Thanksgiving (Canadian one, duh) at his grandma’s house in Toronto, the Biebster thought it would be hilarious to serenade his grandmother naked with a guitar strategically covering his junk. Apparently it was a prank. We’re told granny begged for him to put his clothes back on because, you know, she’s not a 16 year-old fan who fantasizes seeing him naked, she’s his GRANDMA!

“We’re told birthday-suited Bieber went right up to his grandma and started belting out some impromptu lyrics … like, ‘I Loooove you grandmaaaa … how are youuuu … helloooo grandma,’” reported TMZ.

Oh sweet Yeezus! Put that thing away, kid.