Robbie McNulty, 14, was playing basketball by himself at a Cambridge, Mass. park.

If you’ve ever hooped alone on a court, you know your imagination takes you all kinds of fun places. Crossing over LeBron to drive to the basket? Check. Hitting a three-pointer at the buzzer to send your team into the playoffs? Check. Needing to drain two free throws to win the NBA championship? Check that one off, too.

McNulty was likely doing a little of that when suddenly Isaiah Thomas of the Boston Celtics dropped in. This wasn’t his mind playing tricks on him, however.

“He was the only kid there,” Thomas told The Boston Globe. “So I’m like, ‘I’m just going to go get some shots up with him.’ When I walked over, he rebounded his own shot and turned around and I’m like, ‘Can I get a couple shots?’ And he stopped. He didn’t even say a word, like his eyes were so big. He just stopped and froze and I’m like, ‘Pass me the ball.'”

The two played for about 10 minutes, but it made McNulty’s day and then some.

Here’s more on the teen’s experience from Good Morning America, which is also where Thomas surprised McNulty by inviting him to a future Celtics game.