That's exactly what happened to Microsoft last Sunday night when the former daytime show host was on Twitter listing some of her favorite items for the holidays using the hashtag #FavoriteThings.
In the midst of all her endorsements, Winfrey sent out a shout out for the Surface, saying she's already bought a dozen as presents this year.
"Gotta say love that SURFACE! Have bought 12 already for Christmas gifts. #FavoriteThings," she tweeted around 9 p.m. Sunday.
Twelve tablets? That's high praise coming from anyone, let alone one of the most influential people on the planet.
Unfortunately for Microsoft, though, when you see Winfrey's tweet using a third-party Twitter client, such as Echofon, you can see where she sent it from -- and it wasn't the Surface.
Instead, Winfrey used the Twitter app for the Apple iPad, the ultimate rival of the Microsoft Surface, to endorse the newcomer tablet.
Many people won't see the "via Twitter for iPad" label since you can't see it on the official Twitter website or apps, but as TechCrunch reports, the Winfrey tweet highlights a major issue with the Surface: there's still no official Twitter app.
You can still use Twitter by going to the social network's website using the Internet Explorer app, but the fact that Twitter and others like Facebook still don't have apps has been one of the drawbacks to purchasing the Microsoft tablet.