"Christmas at the Old Bull and Bush"

Interact Theatre Company at Arena Stage

Through Jan. 9

Tickets: 703/218-6500

If you're picking up on an extra note of authenticity as Bob McDonald sings "Christmas in the Trenches," an adaptation of a World War I poem, it's probably because the baritone is also a sergeant. McDonald has been part of the U.S. Army Chorus for a half-dozen years.

"I tell my friends I'm in the military and they're horrified," McDonald says with a laugh. True, he did have to go through basic training -- "eight weeks of being screamed at and running at 4 in the morning" -- but now his active duty consists of belting out Broadway tunes, as well as selections from opera and operetta.

McDonald says he's grateful for the variety that "Christmas at the Old Bull and Bush" offers -- it's a rowdy roller coaster of comedy routines, melodrama and lots and lots of music, conceived and directed by Catherine Flye. Where else but there, for instance, would he be able to croon "Wanting You" with a chicken?

"It's pretty cheesy," he acknowledges, "but the place goes insane."

McDonald is also the national anthem singer for the Washington Capitals, and on game nights he has to dash from MCI Center to change into his tux and tails for "Bull and Bush." When he's not spending evenings singing in the Interact show, he's often busy with the Army Chorus, entertaining at White House parties. And trying not to overdo it at the buffet.

Poor guy. "When you're in the Army," he says with a none-too-serious sigh, "they own you."