let me start however by clarifying the "old tee shirts."  way back in 1990 group of women got together and created "the clothesline project."  women and girls who are victims of violence express their feelings on tee shirts that are hung on a clothes line.  it draws on the metaphor (or is it a simile?) of "airing out one's dirty laundry."  

back in the olden days (pre late 1970s), violence and abuse within families was something shameful that was not talked about.  women bore their abuse in private.  there were few laws to protect women and girls from sexual and domestic violence.  the few laws that existed weren't enforced.

the premise of the clothesline project is that a victim of sexual or domestic violence uses the tee shirt to express whatever they are feeling about their abuse.  the tee shirt that you saw that said "rape = not good" was made by a rape victim.  perhaps not the most articulate rape victim.  but it was her expression of her feelings about being raped.  and perhaps the expression "not good" held some personal meaning for her in the context of her abuse history.

the tee shirts are considered empowering simply by virtue of the fact that they exist.  victims of rape, domestic violence, and sexual abuse empower themselves by speaking the truth about their experience instead of hiding it away in shame.  by speaking out, they are proclaiming, it was not my fault.  this was done to me and it was wrong.  they are reclaiming their voices.

every tee shirt you saw hanging their was made by a victim, expressing her (or his) own thoughts, feelings about the crime committed against them.  the value of airing that "laundry" in public is for viewers to pause a moment and take in the reality of the experience of those victims, to  notice how many victims are represented.  to appreciate the pain the victim has suffered and to value their courage in speaking out.

the purpose of the tee shirts is not to empower you.  it's to empower the women who make them, to let other victims know they are not alone, and to encourage other victims to speak out.

here is the url:  http://www.clotheslineproject.org/