star was talking to the morning show anchors about directing a live stage reading of Good Will Hunting
, the 1997 Oscar-winning movie that helped put Affleck and Damon on the map, when the fellow Boston native
appeared in the back of the studio.
"We have someone here who knows a little something about that movie,” George Stephanopoulos announced. “What?!" Krasinski responded. "Is Matt Damon here?”
Upon seeing Affleck, the 36-year-old actor quipped, "Oh, I’m sorry. I didn’t know you had the handsome one.”
Last week, Krasinski revealed that he had cast his wife, Emily Blunt, in the live reading by tweeting out a funny photo. "So I'm casting this #LiveReadNY of GOOD WILL HUNTING, then ran into this #girlonthetrain and thought... yeah, its time we worked together!" he tweeted.
Krasinski did not reveal who Blunt would be portraying but it's likely she's been cast for the role Skylar, who was originally played by Minnie Driver in the movie. It's still yet to be known if Affleck, 44, and Damon, 45, will make an appearance at what is sure to be an amazing reading.
When ET chatted with Blunt
about her husband earlier this month, she confirmed what fans have all been thinking: he's the "perfect man."
“He is funny and warm and bright and confident and a sort of emboldening person to be around,” the 33-year-old Girl On the Train actress gushed, adding that he's "so much more adventurous" than herself.