Meaning of "get on", "get over on", "get in on"

1. She don't want anyone thinking that I'm soft so they can get over on me.

2.They got on me pretty quickly, wrestled me down, and took away my weapons.

3. "Well, now you ain't in the business any more, I may as well tell you you kind of got in on me.

4. My two pups got on him and stretched out.

I found these sentences on Google and wonder what they mean.