Last Friday, John Mayer surprised a 16-year-old girl  he met in a New York City music store by buying her an acoustic guitar without her even knowing.

Julie Fermin was in Rudy's Music in New York City with some friends just looking around when she ran into John Mayer and his on-again, off-again girlfriend Katy Perry. After recognizing him they struck up a conversation. She told People magazine:

I started crying and screaming. I was the luckiest and happiest person alive."

While talking with her, John asked Julie what guitar she liked most in the store. After pointing it out the conversation continued for a bit longer along with some pictures and they then said their goodbyes.

It wasn't until John and Katy left that a store employee told her that John had purchased the guitar for her on his way out the door!

"I was so shocked. I cannot describe all the emotions I was feeling at that moment," Julie said.

She has posted several pics of her with her new guitar on her Twitter page and I'm guessing here, but I'm sure she's been playing that new guitar every day since getting it!