Iggy Azalea performs at Lollapalooza 2014

Iggy Azalea performs during Day 1 of Lollapalooza 2014 at Grant Park in Chicago, Illinois on August 1, 2014.

Timothy Hiatt/Getty Images

Puking, twerking and prosthetic arms: it was all there for the "Fancy" star's set.

Iggy Azalea's performance at Lollapalooza was one of the most anticipated sets of the weekend, and easily the most well-attended outside of the main stage performers on Friday (Aug. 1). The sprawling crowd in Chicago's Grant Park was essentially a field study of millennials: everyone was young, everyone was screaming, and everyone took at least one selfie.

Lolla Day 1 Recap | Iggy Stays 'Fancy' | Full Lolla Coverage

Billboard squirmed its way into the thick of the action during Iggy Azalea's set, and here are a dozen things we saw within the unhinged crowd during the 40-minute performance:

1. Six shirtless dudes walking in single file, fist-pumping and chanting "IG-GY! IG-GY!"

2. A skinny brunette girl softly weeping against the bare chest of her confused-looking boyfriend.

3. A tree selfie.

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4. A muscly dude who declared, "I just realized that I only know one song that she does," when Iggy opened her set.

5. More bucket hats than a dozen ScHoolboy Q videos combined.

6. Multiple young girls vomiting in the darkest corners of the crowd.

7. A sleepy-looking white kid wearing a self-made t-shirt with "WHO DAT? WHO DAT?" spelled out in green graffiti.

8. An African-American teenage girl swigging from a jewel-encrusted flask.

9. A prosthetic arm being used to cheer on Iggy during "Work."

10. A group of three teen girls -- somehow all under five feet tall -- rapping along to every word of "Pu$$y," eyes bugging out with unadulterated joy.

11. A six-foot guy in an Andre Drummond jersey twerking in front of his gleefully shrieking girlfriend, who smacked his booty with delight.

12. A girl demanding to be on her boyfriend's shoulders for "Fancy," being quickly hoisted up… and then toppling over with a frantic yelp.

Live at Lollapalooza 2014