A "moose tail" is a slang term that refers to the outline or bulge created by tight clothing, especially pants, around the genital area. While originally used to describe a visible silhouette resembling a moose's tail, it is now often associated with male genitalia. It is advised to use discretion and sensitivity when discussing or referring to such terms in a respectful manner.
Taint your ass taint your balls ; taint your moose knuckle taint your moose tail.