Scooby Doo 2 Easter Egg - Frank Sinatra Tribute

When they are searching the mansion, Scooby brings Shaggy a bunch of stuff he finds throughout the house. Scooby lays them all on the floor and picks up a hat, puts it on, and starts singing Sinatra's "Strangers In The Night" but instead of the original lyrics he just sings "scooby dooby doo..."
The creator of Scooby Doo came up with his character's name when he heard the song "Strangers In The Night" in which Sinatra sings scooby dooby doo at the end of the song.