probably around 3rd grade or so... although i didn't use them in front of any adults. It was around the age of 12 or 13 that i started telling my mother to "F*** off!" I did that for a few years but i have since stopped. I swear semi often, but I do my best to refrain from being malicious or rude to people. In other words, i don't tell people to "F*** off" anymore.