Justin Bieber Sings 'I'll Make Love To You' to Newly-Engaged Couple

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Justin Bieber performs at the 102.7 KIIS FM's Wango Tango at StubHub Center on May 9, 2015 in Los Angeles, California.

Justin Bieber is up to his (new-ish) old tricks again.

Just days after taking the stage at the W Hotel in Hollywood to perform a jazzy rendition of Boyz II Men's sultry 1994 hit "I'll Make Love to You" (which the guys later approved of), he once again busted out the track, al fresco and a cappella, at the Grove in Los Angeles.

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It all went down Thursday night -- and for a good cause. He was serenading a couple who had just gotten engaged, per TMZ. But when it came to belting out the chorus, he made the future groom get in on the action, too.

Bieber's other request? "Now make out." And they did. Cue the applause.