Passive agressive behavior

i was taught this behavior as a child. it was called being "nasty nice". like doing spiteful things then acting innocent about the fact that something happened.

example: in 7th grade a girl on the bus constantly picked on me about having large breasts. i went to my grandma for advice on how to handle the situation. i was told..."next time you get off the bus carry your books in your hands and 'accidentally' knock her in the back of the head with your elbow. when she says something reply 'oh i am soooo sorry! i guess my big ol' boobs got in the way and i did not see you there'. and innocently smile."

i had no idea that this was wrong. i was told 'this is how southern ladies appropriately express anger without fighting'.

so now that i have been informed that this is wrong...i just keep all my anger inside until it explodes.
how is one supposed to be angry in a good way? i am so way confused!

Can it explode in a good way? I repress anger forever, years, until I'm ready to be done with a person. Then I'm honest with them. I look psycho, because they never see it coming, but I manage to detach myself from them and I get the peace of finally letting them know what they did. Win-win?

Actually, that sounds more pathological than it did in my head...