"The thing is is..." I remember when I first started hearing the double-is. It grated on my ear. At first, I thought it was a local thing--provincial Utahns adopting each others' bad speech habits--but I've now heard at least two people on TV do it.

Interestingly, when I pointed the grammatical error out to people, I discovered that they didn't realize, and often even denied that they were doing it. The double-is is so quick that it goes by unnoticed unless your ears are quite sensitive (perhaps oversensitive) to grammatical mistakes. I have an uneasy feeling that the difficulty of catching it will make it an easy habit to acquire and a difficult one to break.

"Is is" is the new "like".