不要吃我豆腐 is telling someone not to take advantage of me, but specifically in a sexual way, as in inappropriate touches etc. However, the accusation is not very serious in Chinese, and sometimes said in a joking manner. I would translate it as "Don't harasse me!", "Get your hands off me!" etc., but understand that the Chinese expression is softer.
妳真三八: 三八 I think refers to someone who is nosy and likes to gossip, although in recent years it may have become an all-encompassing word such as the "b" word in English, I don't know. In its original meaning, I would translate it as "You are such a busybody", "You are so gossipy", etc. Maybe there are more colloquial ways of rendering this?