The Careless Fairy PSA
The term careless fairy is derived from a Canadian PSA detailing prejudice against homosexuals, specifically how such prejudice relates to the AIDS pandemic. The second line of dialogue in the clip is also the source of Tim's much-loved "Oh hey, queer" sound effect.
It should be noted that there are two versions of this PSA. The edited version has two lines changed from the original. "Oh hi, fag" was changed to "Oh hey, queer", and "Careless homo" was changed to "Careless fairy". It is perhaps the increased ridiculousness of the edited lines, especially the latter, that has caused them both to become a frequent part of the DV world instead of the original, supposedly more offensive lines.
It should be further noted that Tim played the original clip on the show on August 22nd, 2006 - a while before he played the edited version.