What is "getting off on"

Usage examples of "getting off on".

I was getting off on teasing him, of course, so my nipples stood out like bullets.

I imagine that has something to do with the way I feel, and my inability to write, but--but I'm getting off on a sidetrack.

Blake, I like you, but I feel it is my duty to warn you that you are getting off on the wrong foot.

Rosenthal knew he was really getting off on the wrong foot here, and there didn't seem to be any way to make himself more acceptable.