This idiom or expression means:

At risk.

I’m risking everything, and I have to be careful. My neck is on the line, you know!

Also:
My ass is on the line! (Same thing, but not polite.)

This idiom or expression means:

On risky grounds.
In a dangerous situation.

When someone says “You’re walking on thin ice,” they mean “What you’re doing is risky. You should be careful!”

A. I’m dating my boss’s daughter, and he doesn’t know!
B. You’re skating on the thin ice corner of the lake, stupid!!

Also:
Slippery slopes.
Slippery grounds.

Also see:
Walk on eggshells.

This idiom or expression means:

Taking the risk of.
Running the risk of.

At the risk of offending you, here’s what I think, means:

I hope you don’t mind, but I think you’re wrong;
I may be offending you, but I think you’re a moron;
I hope I’m not upsetting you, but I think you’re crazy; etc.

This idiom or expression has to do with:

Increasing the risks.

When you say “Stakes are high,” it means “This is a very risky situation!”

As an expression, playing Russian roulette means taking a huge, huge risk. Playing the real Russian roulette, however, means risking your life.