From Homestar Runner Wiki
Douglas is a random name that Strong Bad used during cheat talk to test the speech ability of The Cheat, because a viewer could not understand what The Cheat was saying, but to no avail. Strong Mad couldn't say "Douglas" either, but Strong Sad did when Strong Bad slammed his keyboard into him. The branch outside Strong Bad's window in his computer room makes a sound like "Douglas" by scraping against the window. Later, in Strong Bad email sibbie in an Easter Egg, Strong Mad successfully says Douglas, so Strong Bad gives him a gold star.
The variant Doug has also been used several times.
- Main Page 14 — Hidden in the Flash File is the text "DOUG".
- Email cheat talk — Strong Bad tries to get The Cheat and Strong Mad to say "Douglas", with little luck. Then Strong Bad slams the keyboard into Strong Sad's stomach, which causes him to say "Douglas".
- Email sibbie — During the Easter egg scene, when Strong Bad tries to teach Homestar Runner to say "Fhqwhgads", Strong Mad appears and says, "Douglas!", to Strong Bad's amazement.
- Email the facts — Strong Mad creates a clay animated short called Doug the Dino.
- strongbad_email.exe Disc One — The intro video makes reference to Douglas.
- Sbemail 150?!? — Strong Sad considers conjuring up a treatment for Doug the Dino.
- Happy Hallow-day — Homestar Runner says "Thank you, Doug" while talking to himself.
- 8-Bit is Enough — The name Douglas appears in a fake credit sequence.