You slow blink. This is you telling the cat "I don't see you as a threat. I feel comfortable around you."

Or you could show them your belly. Tracy Morgan style. Just show your belly. It says to the cat "This is my most vunerable part of my body. And unlike you, I only have TWO nipples. Which means I am less vunerable then you! Six nipples is more weak points than two nipples! Now bow before me, god of the Egyptian roman times empire! I can crush you like a bug with my belly, which as we're established is the most vunerable part of the body!"

And they slow blink back to you!!!

Oh! Oh you wanna go??? I'll slow blink right back, bitch!!! I'll have a slow blink war!!! We'll see who's not a threat!!! I even invade your privacy, and steal the poops you burried in that box!!! I'm taking them awwwaaayyyyy......