They were goofing around in the front yard after schoool.
Why she had her shirt off, I don't know, but apparently it caused her companion (male? female?) to get out a camera. I love how candid her expressions are. She's pretty sexy in jeans and no shirt, but she's not trying to be sexy, in fact, it looks like she's cracking up.
Even sexier, she's clearly in the front yard by the driveway; pretty brave to be topless when someone could drive by or pull up. Maybe even her parents.