I know you want to be seen as hip and cool. I know you want your kids to be seen as hip, cool, trendy, and irreverent. That's great.
However, you sent your child to school wearing a t-shirt that says: "I'm allergic to homework." Or something along the lines of "I'll do my homework (right away) (in a few hours) (whenever I feel like it) NEVER." Or "I'm only here for recess." I'm sure that you, looking back on your school days, find these shirts adorable and funny. I found three of these shirts on students (all boys) today. My opinion of your child suddenly goes from "hey, look, a kid" to "hey, look, a self-centered brat who hates learning." Not only does it immediately change my perception of a child and his behavior, but it also suggests to the kid that it's all right to be flippant about schoolwork.
So here's my advice: stop it. Your children don't buy their own clothes. You do. Don't send your child to school with an anti-school shirt. It's not cute.
Also banned: shirts that say "Diva", "Princess", "It's All About Me", etc. You think it's cute. We just think your kid's an asshole without getting to know them first.