Lightly spray large mixing bowl with nonstick cooking spray. Add popcorn.

Spread plastic wrap on cookie sheet; set aside.

In medium saucepan, melt butter and marshmallows; stir until mixture is smooth. Stir in peppermint extract. Pour over popcorn, mixing until well coated. Let cool 2 minutes.

Spray hands with cooking spray and form popcorn mixture into 3-inch balls. Gently press colored sugar onto balls. Let sit on prepared cookie sheet until cool and set.