Lance Cpl. Timothy Swann Jr. gave the T-shirt to his brother, 13-year-old Jordan Griffith, of Ellisville, shortly before deploying to Afghanistan.
"Jordan just idolizes Timothy," their mother, Sandy Griffith, told the Marine Corps Times. "Timothy gave him the shirt and told him, 'Always remember you're a leader, not a follower.'"
The front of the shirt depicts the head of a bulldog with the words "If you are not the lead dog." The back says "The view never changes" -- and bears an image of the dog's rear and genitals.
South Jones Elementary School officials told Jordan to turn the inside-out or have his mother bring him a different shirt, but Sandy Griffith chose to pull her son out of school for the day, the Marine Corps Times reported Wednesday.
"My father made a joke that the woman who told him to turn the shirt inside-out must have been in the Navy," she said.
School Superintendent Tommy Parker said the administration didn't have a problem with the Marine Corps, but some of the school's teachers were upset because "all the details are there," in the depiction of the dog.