"Baby" Bieber The Justin that started it all, and still your grandmother's favorite Justin. To get this look, you'll need a purple long-sleeve shirt, black pants, a bowl haircut and a willingness to do that "pop the collar and then point" thing he does in the video. If you can get a guy to follow you around and dress like Ludacris, so much the better.
Fedora Bieber This might be the worst Bieber of all, but it's also one of the easiest to pull off. Throw on a fedora (preferably, for your purposes, purchased from Urban Outfitters), big sunglasses, and a track suit. Step out of a giant vehicle, stare blankly, and everyone will totally get that you're pulling off this Bieber look. (It's better than that time he covered Boyz II Men in a different fedora.)
Mugshot Bieber Who could really be made at Justin after seeing that little punim? All you need to pull off his mugshot look is a bright orange/red v-neck t-shirt, some gel to slick your hair back, some makeup to give yourself dark circles under the eyes and a glazed-over smile all night long.
Emotional VMAs Bieber Nothing gets me more worked up than Justin Bieber's emotional performance at the VMAs -- mostly because he looked like he belonged at a Kelela EP release rather than this year's technicolor Moonman ceremony. Plus, his Kate Gosselin coiff/missing member of The Cure red carpet look feels like way too much work, so you know, might as well just stick with the basic Biebs aesthetic. All you'll need is a black trucker hat, a novelty costume head mic (diva costume sold separately) and an all-black fuccboi look of your choosing (trackies, plain tee, etc). Oh, and some eyedrops.
"What Do You Peen" Bieber Ok, you're going to need a nude body stocking (like this one from "Elegant Moments," where your mom totally shops) and either a strap-on or a dildo. But if you don't have that, you can just put anything in your underpants that you think best evokes Bieber peen. (An eggplant, a ballpark frank that plumps when you cook it -- whatever LENGTHS you need to go to keep your costume cheap and easy, right y'all?) If you want, have a friend draw tatts on for you with some eyeliner. (Just do his chest ones, ain't nobody got time for those sleeves.) Gross blonde wig optional.