[DrDubzz]

Here's what I found for the Navy
6. TATTOOS/BODY ART/BRANDS. Three Criteria will be used to determine whether tattoos/body art/brands are permitted for Navy personnel while wearing civilian clothing: content, location and cosmetic.



a. Content. Tattoos/body art/brands located anywhere on the body that are prejudicial to good order, discipline, and morale or are of a nature to bring discredit upon the naval service are prohibited. For example, tattoos/body art/brands that are obscene, sexually explicit, and or advocate discrimination based on sex, race, religion, ethnic, or national origin are prohibited. In addition, tattoos/body art/brands that symbolize affiliation with gangs, supremacist or extremist groups, or advocate illegal drug use are prohibited.
b. Location. No tattoos/body art/brands on the head, face, neck, or scalp. The neck area for purposes of this regulation is any portion visible when wearing a crew neck T-shirt or open collar uniform shirt. In addition, otherwise permissible tattoos/body art/brands on the torso area of the body shall not be visible through white uniform clothing.
c. Cosmetic. This regulation does not prohibit cosmetic tattooing to correct medical conditions requiring such treatment. For the purpose of this regulation, cosmetic tattooing refers to medical or surgical procedures conducted by licensed, qualified medical personnel.


so I guess as long as a t-shirt would cover it, and it's not a swastika (sp) I think I'll be ok