Well, the other images hint that it's a complete mystery, check out that MS Paint face on the third pic (that's obviously fake), so the Grinch thing just adds to the "what COULD it be? It could be a fox game, a box game, a socks game, you don't know! Mwahaha" vibe. Besides, there might be people crazy enough to bid on a fruitless auction (and if they actually get a mysterious game, so much the better. I suppose they didn't consider it might be a cartridge with a bomb or dangerous chemical inside).
If there was an auction for an unreleased game called Half-Dress: Freeman Bangs His Crowbar, would you Glorb buy it?
...that's my groaner entry.