Front of shirt could either have:
I hate my guts (b/c i liked this one)
I got to go, I really got to go...
I can't eat that...
I Sh** You not. (an old saying meaning "I'm Serious".)
OK that may have been too bad for this post or a shirt.
I just thought of another one for a bumper sticker. Instead of I break for garage sales or whatever, how about:
I break for porter potties
Someone who knows how to how to do polls should do one with the top slogans so the community can decide a winner. just for kicks.