THERE’S nothing sacred on “Late Night with Conan O’Brien” – except Conan O’Brien’s private life.

On last Thursday’s “Late Night,” guest Dom DeLuise congratulated O’Brien on his “engagement with Liza” – alluding to Liza Powell, O’Brien’s new fiancee.

According to the website tvbarn.com, O’Brien laughed nervously and replied that he doesn’t discuss his personal life on the air, saying, “We’ll edit that out for tonight.”

And they did. DeLuise’s comments never made it onto the show.

O’Brien met Powell – an ad exec from Seattle – when she appeared on a “Late Night” skit about advertising.