It's hard to remember a time when suits were considered boring and stuffy, reserved only for the office or serious occasions. These days, our closet doesn't feel complete without one. Think about it: When wouldn't a suit work? They can be worn casually, made to look fancy, and are also sexy as hell — especially when styled with a peek-a-boo bra, AKA a trend that's seemingly everywhere as of late.

Katie Holmes is the latest star to skip a shirt, wearing her blazer with a bralette in lieu of a top while on the set of a shoot. Along with her comfy satin pants, this outfit is one we’d dare ourselves to try during the holiday season. We can easily picture it replacing our go-to black dress for New Year's Eve.

Sleek and sexy, casual and cool — this styling trick is all the things, and Katie isn’t the only one who is on board.

Tracee Ellis Ross also opted for a peek-a-boo bra under her oversize JW Anderson suit while attending AFI Fest.

Kelly Rowland wore a similar look to the same event, pairing a lacy black option with a white suit. We love a contrasting look!

Sofia Richie proved this trick doesn't have to be so formal. The star wore a blazer and bra combo with jeans while at a Kate Somerville event.

This trend popped up on the Spring 2020 runways, so we're sure it'll be around for a bit. Michael Kors gave it a warm-weather spin with a gingham set.

It looked slightly more '70s in Fendi's Spring collection, when a brown bra was styled with a long suede jacket.

Zimmermann also included a peek-a-boo bra, but it was patterned, rather than solid.

In real life, the lingerie trick can really spice up a blazer and skirt pairing.

Want to give your baggy pants a sexy spin? A blazer and a bra to the rescue.

Gigi Hadid went with an all-black combination during a night out, and now we're wondering if we should do the same.

It's definitely a trend to keep in mind for warmer weather. A bra and blazer is easy and breezy, and still works with a pair of shorts.

Plus, you can use it as a way to add a pop of color to an everyday outfit. The possibilities are endless.