Can i get in trouble for having a picture of a razor blade on my backpack?

ok, im completly in love the musical sweeney todd,(ok, more obsessed really) and i was wanting to get an S.T. backpack for highschool next year. the thing is, on the design on it has a straight blade, and idk if i'd be allowed it in school or not, considering my friend always wore a shirt with a razor on it last year in middle school, and the teachers never said anything about it. so would it get me in trouble or not?