Murdock: Here, take care of Waco for me. (He pronounces it "Wacko.")
Hannibal: That's Waco, Murdock. (He pronounces it "Way-co.")
Waco is, of course, a city in Texas that is home to the Texas Ranger Hall of Fame, among other things. It was also the name of a 1966 western movie starring Howard Keel, Jane Russell, and Star Trek's DeForest Kelly in a bit part. There's also a "Waco Kid" in Blazing Saddles and "Waco Johnnie Dean" in Winchester '73.
However, Murdock pronounces it "Wacko" because he's a pilot. The Weaver Aircraft Corporation was founded in Lorain, Ohio, in 1920 and was quickly nicknamed "Waco" (pronounced "Wacko"). Murdock flies a Waco biplane in the second half of the two-part pilot episode "Mexican Slayride."