Can someone wear underwear with that dress? That become the nagging question in "O! Say, Can You Sew?"

With a budget of $200, the Project Runway All Stars head to the United Nations, where they choose a nation's flag as inspiration. Unfortunately for them, their choices are limited. The goal is not too take the flag too literally but still not miss the mark. Does anyone get it right? 

Joanna questions almost everyone. Jerell's working with India but, as Joanna says, his dress looks like it belongs on a doll in an Indian tourist shop. He seems to swing from one end of the pendulum to the other. One week his outfits are gorgeous and the next they make me cringe. This week, I'm cringing.

Austin's struggling with all of primary colors on the Seychelles flag. The blue and yellow he uses don't seem to work and the flowing chiffon looks unfinished. He's a talented designer but it seems like he's lost his mojo these last few weeks.

Then Joanna asks her question of the night: Can a woman wear a bra with this dress? Austin says he thinks she could, but looking at that outfit Joanna isn't buying it and neither am I.

Mondo's right when he says Michael's Greek inspiration is more Greece Frightening than Greece Lightening. Oh Michael. He's so proud of his Greek heritage that the dress ends up looking like a beauty pageant toga. 

Back to Joanna's nagging question. With the very low cut back, there's no way anyone can wear a bra with this dress.

Speaking of Mondo, his Jamaican inspired dress is really rather stunning. It's long and black with green and yellow color blocks along the back. It's high on funky elegance but it doesn't scream Jamaica to me. Maybe the whisper of reggae is enough.

It's a great dress but it again fails the underwear test. Unless you're a pencil thin model with A cup breasts you can't wear this thing.

The entire theme leaves Joanna thrilled with Mila's half and half dress if only because you can wear a bra with it. I'd joke that you could wear a girdle under Kenly's 1950s inspired silhouette, but I'd be lying. No one wore skirts that short in the fifties. And leave it to Kenly to find a heart print that looks like polka dots.

When we hit the runway we find Catherine Malandrino, fashion designer who did a whole line inspired by the American flag as our guest judge. 

On to the runway results:

The Top Three:

• Mondo's Jamaican look. Georgina loves it but Catherine complains about the faux dreadlocks he's given his model. Isaac thinks the green and yellow back is too in your face.  Can the back really be in your face? Personally, I think it's gorgeous. I could never wear it. (I'd need a bra.)  But I love it.
• Kenly's Chilean dress. Georgina likes the young attitude. Angela says this is the modern, cool girl in Chile. The girl wearing this dress is embarrassed by her mother's poncho. But is it daring enough? I like it more than I thought I would. Isaac warns Kenly not to repeat this style next week because he's noticed she's prone to do that.
•  Michael's Greek look makes the top three and I'm a little surprised. It's screaming beauty pageant. Catherine thinks the draping has too much volume. Angela hates the blue bow, as do I. It looks like it belongs on Christmas gift. I really thought Michael would end up on the bottom with this.

The Bottom Three:

• Jerell's Indian goddess looks like she's going to a costume party. Georgina says he has too many ideas in one dress and it's heavy handed. It's just a bit of a mess.
• Austin's Seychelles dress fairs slightly better. Georgina thinks it's a pretty dress but the color use is off. It just doesn't quite work but Angela says it's not the worst dress she's seen on this show. Now there's high praise. Yikes!
• Mila half and half Papua New Guinea dress has few fans. Isaac thinks it looks Russian. The judges call it schizophrenic instead of modern and graphic.

And the winner is: Mondo! He grabs the top spot once again and deservedly so but I think Kenly gave him a run for the money this time.

Going home: Mila! For the second time I thought it should have been Jerell. That Indian costume was horrible.  'm not Mila's biggest fan but at least her dress was original and interesting.

Kenly's the only woman left but the way Austin and Jerell are flailing her odds may be good to make it to the end. If we learned one thing tonight, it's that underwear is optional on Project Runway.

C. Orlando was a TV Fanatic Staff Writer. Follow her on Twitter.