It turns out, it is a well known fact: people are attracted to members of the opposite sex more when they see dilated pupils. This effect has been known for half a millennium. In the 16th century Italian women would put drops made from the deadly nightshade plant (one of the most poisonous plants) into their eyes to dilate their pupils and, hence, look more attractive to males. This gave the the plant its other name Belladonna which is Italian for Beautiful Woman. Today when you go to the eye doctor and they dilate your pupils they are using a synthetic form of the active ingredient in this same plant.

Careful study showed that indeed men were more attracted to pictures of women with the pupils enlarged in the 1960's and it turns out that women show the same preference. By careful scientific study I mean they took pictures and simply colored in the iris black. They then showed them to test subjects and asked them to rate their attractiveness. The current theory as to why people find others with dilated pupils more attractive revolves around sexual selection. This is mainly due to the fact that this preference starts with puberty. It is most likely related to the fact that when people are aroused and interested their pupils dilate. So, the theory goes, if you are talking to a potential mate and their pupils dilate you have evidence that they are interested and your efforts have more of a chance to pay off... with the fucking. 

So in the end, Lady Gaga and those teens are tapping into an old Italian secret of how to use a little poison in the right place to catch a mate.

I tried to find a picture of the plant to go along with this but the pornstar of the same name makes image searching difficult to do.