It’s the most common phrase heard around these parts right now, other than Merry Christmas: “Who dat say dey gonna beat dem Saints? Who dat? Who dat?”

So far this season, no one has, as the Saints are 11-0 heading into today’s game at Washington at noon on Fox.

But where did “Who Dat?” and the Who Dat Nation that follows the team come from? And when did the Saints adopt it as their slogan?

It is widely believed that “Who dat?” began in the late 1800s in New Orleans during minstrel shows and Vaudeville acts. The chant was adopted by jazz and big band-era musicians and bandleaders in the ’20s and ’30s.

Legend says it did not hit the football fields of Louisiana until years later. There are countless claims to the origin of the chant and its ties to football. Some of the most common are:

• Southern University. The school in Baton Rouge lays claim to the chant, using it in the late 1960s as “Who dat say dey gonna beat dem Jags?” High schools in and around New Orleans also claim the chant, using it in the 1970s at football games.

• Dalton Hilliard. The Hilliard claim is the most popular. He played for Patterson High in the late 1970s. The team had been wretched for years, but Hilliard and the team started winning. Fans in the stands began asking, “Who dat?” in reference to the team that eventually reached the state championship game in the Supderdome. The chant then followed Hilliard to LSU and the Saints.

• The Queen City’s Who Dey: Cincinnati claims that, in 1981 after many losing seasons, the team started winning and fans asked “Who dey?” in reference to the team. Many Cincinnatians still believe the Saints stole the Who Dey? and changed it to Who Dat?

Those are all wrong, at least according to our own news reporter Danny Barrett Jr., a New Orleans native and season ticket holder.

He doesn’t know who started the chant at a high school or college, scoffed at Cincinnati’s claim and said the chant became a huge part of Saints’ lore in 1983. That year, the Saints were winning games and were even talking playoffs. Not until the last game of the year — a loss to the Los Angeles Rams — was the team eliminated from the playoffs. The wins, though, led to the recording of a song by New Orleans’ own Aaron Neville and the Singing Saints.

The song, recorded by New Orleans musician and producer Steve Monistere, has Neville singing the lead and Saints offensive lineman yelling the “Who Dat?” chant. The song mixes the chant into the jazz standard “When The Saints Go Marching In.”

Out of that one song, a nation was born — the Who Dat Nation — and its ranks are growing and growing. According to whodatnation.com, “the Who Dat Nation is comprised of New Orleans Saints Fans, all of whom are famous for the chant.”

The Saints have five regular-season games to play before the playoffs. There is still room in the Who Dat Nation. It’s easy to join. Learn the chant and bellow it with pride starting today at noon against the Washington Redskins.

“Who dat say dey gonna beat dem Saints? Who dat? Who dat?”