If you’re confused about when to flaunt them and when to cover up read below.

Just one missed blouse button and your “girls” can suddenly go from classy to trashy. Whether you meant to show off the goods on purpose or you’re just too busty to help it, learn how and when to give your cleavage its stage time with our 3 rules for best breast etiquette.

The average breast size has grown from a 34B to a 36C since the 1970s and clothing styles are smaller and snugger. So it’s no wonder the line between “Nice!” and “Look at those!” has blurred.

“I don’t think women are stupid,” says Elisabeth Squires, author of bOObs: A Guide to Your Girls. (Seal Press). “I just don’t think anyone knows the rules.”

Rule #1: Acknowledge the obvious.
Sex sells. And like it or not, breasts get beer sold and burgers bought. It’s not such a stretch to realize your ta-tas are more likely to get checked out than, say, your knees or collarbones.So do a double take in the mirror before walking out the front door in the morning.
“[Women] understand the power of breasts in general, but they don’t understand the power of their own,” Squires says.
You may aim for different effects depending on the situation, but understanding how and when to tap into the power of your cleavage will help you achieve the desired result anytime, anywhere.
“We have to realize that breasts are your femininity and sexuality at the same time,” Squires says. “That’s what the power of cleavage is all about – using your sexuality or not.”

Rule #2: Sometimes less is more.
In some industries, it’s appropriate – in fact, required – to play up your cleavage: entertainment, fashion, Hooters, to name a few.“If cleavage isn’t in your job description, don’t write it in,” Squires says.
Too much boobage, and you may end up perceived as sexual, not professional.
“Showing a lot of breast is a distraction, especially in the workplace,” she says. Wear a very low-cut wrap dress or shirt, and everyone will focus on the boobs.
“We all need to be appropriate and be responsible for the message we send out,” Rothschild says. “Think before you even enter your closet what your image is going to communicate.”
So buy a full-length mirror and take a look at yourself. If your breasts are standing out, “that’s probably inappropriate,” Squires says.Don’t reveal more than an inch of cleavage at work, Rothschild says. The same holds true for your company’s holiday party and meeting your boyfriend’s parents for the first time.

Rule #3: Sometimes more brings more.
All bets are off when the sun goes down. Feel free to flaunt your curves and play up cleavage for a night on the town. This is the time to pair a push-up bra with a plunging neckline or, if you’re small-chested and daring, go with a sexy backless number and skip the bra. Revealing 2-3 inches of cleavage during off-hours will get the job done, Rothschild says, but she cautions: “If it looks like you’re going to pop out, you’ve gone way too far.”
Think of your cleavage as an accessory, and make sure it suits your outfit and the occasion.“Or, quite frankly, you might be an exhibitionist, and that’s OK too,” Squires says.