The comedian and sports fan said "this isn't gonna play well in New Jersey" as he put on a Cowboys jersey with his name and No. 9, the same number as Dallas quarterback Tony Romo.
Crystal, a native New Yorker, is in Dallas through the weekend for performances of his autobiographical one-man play "700 Sundays."
He spent part of Tuesday offering pumpkin pie and visiting with diners, serving up one liners such as "how about this Cowboy?"
Crystal, a longtime fan of baseball's New York Yankees, said he wanted to pitch in because he admires the Cowboys and the NFL franchise.