Oklahoma State isn't a legendarily good program--they're very up and down. Even aside from the week brought up previously from last season, it wouldn't be hard to find a week when both lost--the toughest part, honestly, and this is no shot at OSU, is finding a week when OU lost.
Although that happened this year and last year (OU lost, OSU won) and of course every year that OSU has won Bedlam.
But yes, in general, for the last 12 years or so, OU has lost something like an average of 1 regular season game per year. Something ridiculous like that.
So the most difficult scenario to find recently is where both share a loss on the same weekend, but OSU has had some terrible stretches there, and the post-Switzer years were a lost decade for OU.
Since 2000? Different story. OSU has slowly grown into prominence, and of course OU has been a national title hunter again for several of those years.
Still hope Okie St. wins Bedlam and takes the conference title for themselves. They would be electrifying in a BCS game.
Plus, Boomer Sooner always sounds like the song that plays in the head of a drunk circus clown, over and over and over again, until he passes out, crashing his miniature bicycle into the cage of the dancing bear.