A day late (and slightly shorter than usual), but here's the Spy PSA:
The words “PUBLIC SERVICE ANNOUNCEMENT” appear on the screen. After a few moments, the RED SPY decloaks and fades into view.

SPY: Gentlemen.

The SPY lights a cigarette and puts it into his mouth.
SPY: I come before you today in response to the Sniper’s allegations that I am not polite. It is my argument that it is the Sniper who is not polite. He married a kangaroo, lives in his van, and pisses in jars, which he then throws at people. If that is not the very definition of impolite, than I don’t know what is. And yet he still insinuates that I am not the epiphany of politeness. I am very polite. You can just ask his mother.

The SPY clicks the slide-clicker he is holding with a devious smile and changes the background to a picture of the SPY and the SNIPER’S mother.
SPY: Or, if her opinion doesn’t persuade you, then ask the Scout’s mother, Heavy’s mother, Engineer’s mother, Soldier’s mother, Medic’s mother, or Demoman’s mother.

As the SPY is talking, he clicks his slide-clicker repeatedly to change the background to pictures of him and the women he is talking about. Once he is done talking, a picture of the SPY and DEMOMAN’S mother takes up the background.
SPY: In fact, you can ask the mother of any class… except the Pyro. The Pyro’s mother has been the only woman who has ever rejected my advances, and it depresses me so.

The SPY flicks his cigarette in shame.
SPY: That was this morning, actually. I had the BLU intel, I had just got done mail-ordering the brand-new fireproof Spy suit from Mann Co., and I was being my usual polite self in general, whe-

The SPY is interrupted by a noise which sounds like a PYRO. PYRO’S MOTHER barges into the room, dressed in a blue fire-retardant suit and holding a flamethrower. A flower is taped on her gas mask where her ear would be.
PYRO’S MOTHER: HUDDA-HUDDA-HUH!

PYRO’S MOTHER ignites the SPY and sets the set for the PSA ablaze. The fire quickly spreads until it consumes the camera and changes the screen to a notice which reads, “We are experiencing technical difficulties. Please stand by.” After a few moments, the screen goes completely white and Saxton Hale walks onscreen. He is shirtless, and has some deep scratches on his face.
SAXTON HALE: Hello there, ladies and gentlemen. Pardon my appearance, I just wrestled a bear inside the burning PSA studio. I am Saxton Hale, president of Mann Co. I regretfully inform you that our main broadcasting facilities have been destroyed and our Public Service Announcer has been… barbequed. We are currently relocating all equipment to a subsidiary of Mann Co. that makes curtain rods, so check back next week for a final PSA. In the meantime, I recommend passing the time by buying some of our new Mann Co. products! Pyros got you down? Do you keep losing your disguise to the flames, or is your invisibility made useless by fire? Then try the new Mann Co. fire-proof suit! It uses the latest Spytech technology to make it completely impervious to fire, while still remaining elegant and fashionable. Just call 555-5555 and tell ‘em Saxton sent ya!

Saxton Hale walks offscreen. We can hear him smashing a window and jumping onto a nearby helicopter as the screen changes to the Mann Co. logo and fades out.

To make up for it, I'm going to write an extra PSA next week.