Invader ZIM Easter Egg - TV's Frank!

In Hamstergeddon, the man that runs out from under Peepi and stops (wearing the purplish-kinda shirt with the moon on it) is TV's Frank, or Frank Conniff, who was the head writer on the show for part of the first season. (He was also on MST3K) He's also at the end of that episode in the screen saying no animated animals were hurt (or whatever it says...).

In Door to Door, he's the man getting his mail (or his paper...I can't remember which...)

He's also in Invasion of the Saucer Morons. Frank is the Frank of "The prophecies as foretold by...Frank." (The one who says "Yup. Told ya they'd come.)

I saw him a couple of other episodes, but don't remember them now...