Maybe you wear a uniform or follow an office dress code Monday through Friday, and on the weekend, you like to have a little fun with fashion. That notwithstanding, your friend’s wedding isn’t the place to test drive your new romper or rock those jeans you just splurged on. But you already knew that, right?

There are a few gray areas when it comes to appropriate wedding guest attire. Maybe that cocktail dress has a questionable hemline – or it might be the same color the bridal party is wearing. I’ve been to my fair share of weddings, and there’s always that one guest who turns up dressed completely inappropriately. There are plenty of clothing options that’ll turn you into an unintentional eyesore at any union.

Something Skimpy: Nothing screams “look at me” like a skimpy outfit. There’s nothing wrong with showing off a little leg or décolleté every once in a while, but there’s a time and place for such things, and weddings aren’t one of them. I have spent hours watching guests tugging their dresses down and then adjusting them back up only to have to repeat that over and over again. Other guests will notice. It looks hilarious, but I’m sure it’s quite uncomfortable. No, you’re not exactly showing up the bride, but showing off your assets is a surefire way to take away from her big day, so don’t do it.

Jeans and a T-shirt: I don’t care how casual the wedding is and how laid-back the bride in question might be, attending in jeans and a T-shirt is not an option. It doesn’t matter if it’s on the beach, in your mom’s backyard, or even if you don’t know the couple very well. If you’re bothering to show up, the least you can do is throw on a dress. Also, just to be clear, don’t even think about slipping on a pair of flip-flops. Pumps, heels, flats, loafers and sandals are a go, but plastic footwear is a huge wedding no-no.

A Tiara: You’d think I wouldn’t even have to mention this one, but you’d be surprised by what attention-seeking guests have tried to pull off. So, I’ll just state it plainly: Do not, under any circumstances, wear a tiara to any wedding other than your own. Not only is it disrespectful to the bride, it’ll just make you look desperate and ridiculous. This rule, of course, extends to crowns, ornamental headbands or anything else that could be mistaken for a tiara or any other headpiece the bride may choose to wear.

A Pantsuit: You’re going to a wedding, not a meeting at the office! Drop the business persona and show your style in a skirt, dress or any kind of clothing that would look out of place with a coffee stain. This is a celebration of two people choosing to unite their lives together forever, so the least you can do is find something that isn’t overly stuffy and business to wear. I am not just talking about your standard black or charcoal suit. This rule also applies to pretty pastel skirt-jacket combos. They might work for a dinner event, but they just set the wrong tone for weddings. Yes, we know some very powerful women frequently wear pantsuits, but even Hillary Clinton wore a vibrant dress on Chelsea’s big day, and if she can do it, you can, too.

White: It’s never a good idea to wear anything that could be mistaken for a wedding dress. Avoid wearing white. Unless you were invited to a white-themed wedding, don’t take attention away from the bride by showing up in a white gown. Trust me, people will talk!

Ladies, wear appropriate undergarments: In other words, please wear underwear, or Spanx, or something under your dress. This is especially important if you decide to wear something short. I have witnessed many female wedding guests on the dance floor who show off more than I think they intended.