1983

"This is my 200-pound bag of Awwww Gratin potatoes! It's an '83!"

There have been times in the Homestar Runner universe that the characters referenced the year 1983.

[edit] Appearances

Email autobiography — Strong Bad starts out by saying, "This email is brought to you by a grant from The Cheat." A logo shaped like The Cheat appears. Above it is written "The Cheat" and below it in quotes is written "since 1983".
Email the bet — The King of Town has a 200-pound bag of Awwww Gratin potatoes dated 1983.
Baddest of the Bands — When Bubs asks him, Strong Bad blames Coach Z for vandalizing The Stick. Bubs says that Coach Z hasn't pulled that stunt since Halloween of '83.
Dangeresque 3: The Criminal Projective — Dangeresque claims that Professor Experimento got him kicked out of the Space Program back in '83.