The 'Beautiful Girls' singer has revealed how he and the teenage pop sensation penned their track together during a late-night jamming session at Sean's house.
He said: "Me and Justin have been friends for the past two years. So one day he was like 'yo' and said he wanted to do a record with me.
"I was like 'let's do it, I'm ready!' and he came down over the Superbowl weekend and slept over at my house. We banged out a couple of records and 'Eenie Meenie' was definitely the most special one."
The 20-year-old singer-and-rapper has a lot of respect for Justin, 16, because he is such a hard worker.
He added to MTV News: "Justin's definitely a cool kid, man. I've worked with a lot of people but he's definitely one of the most fun and young, like he reminds me of myself 'cause I'm just like a big kid at the end of the day. He's very happy and energised and hardworking too.
"I was 17 years old when I came out. I definitely could be a big role model to him, like a Big Brother figure to him."