I dropped the F-bomb in 6th grade on the bus one day - not only was I reported to the principal because I was heard within earshot of a faculty member, but the bus driver was obligated to tell my mom when she was waiting for me at the bus stop. Needless to say, it was the maddest I had ever seen her, she was screaming like a banshee at me the rest of the ride home and everything.
And the ironic thing is once I turned 18, she was fine with me swearing like a sailor - I probably say the S-bomb more than any cuss word there is.