Boob-baring and bland, dueling dresses and a 90's throwback -- stars are rocking all the wrong trends this week!

Sometime it's hard to tell if a celebrity is just selecting a sexy outfit or if a full-on wardrobe malfunction is the ultimate goal.

Bradley Cooper's girlfriend Suki Waterhouse stepped out at the Serpentine Gallery Summer Party in London on Tuesday, sporting a rose-colored Burberry Prorsum sundress that could easily expose her breasts with a small gust of wind or awkward pose!

The color also was a little drab on the blonde beauty, and aside from that plunging neckline, there's not much to the daring ensemble.

Keira Knightley landed on our worst dressed list this week for donning this duel-level Chanel dress to the Serpentine Gallery event. Did the "Begin Again" actress forget to take off her slip before throwing on the high-fashion mini?

We love the candy-colored embellishments on the asymmetrical cocktail dress, but the white "dust ruffle" at the bottom is totally unnecessary -- see the full thing in the gallery.

Moving on to more confusing fashion statements, we raised an eyebrow when we saw Zendaya's Emanuel Ungaro ensemble at the BET Awards on Sunday. Is it just us or did it look like she borrowed something that Jennifer Lopez wore back in the late '90s?

But these celebs weren't alone -- see more of this week's worst dressed stars in the gallery above!

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