I think this question personally can go both ways here. I feel there is solid evidence supporting a nice ass grab as a friendly gesture, but it can also be offensive. Also I would advise all of you to take notes, I am an expert on this shit.
When friendly
- Power bottom
- Its a girl you have known for a while, and she is comfortable with it.
- You have already kissed
- If your casually making out a soft grab of the tush is just fine.
- You are about to start anal.
- You are hitting her doggy.
- The women is clearly excited and flirtacious toward you
- 69 its encouraged
When Offensive
- In church.
- The father is present.
That is really all I can think of. I honestly would just go for it in every other situation, nothing really that terrible can happen.