Lol, worst "paranoia" I've had was the feeling that someone was watching me, (same as if I was sober, and only happened at night when I was alone walking.)
That, and one time walking home I noticed that a house kinda looked like it had a face (you know, the traditional "door = mouth, windows = eyes crap" and thought it was kinda funny, knowing that that was probably how my "paranoia" manifests on weed, if you could even call it paranoia.
But yeah, I've had a conversation with my grandmother completely fucking high. Basically I had a party when my parents were gone. They told my grandparents to check up on us. I never knew they were coming. I had just got ripped, when my grandmother came in, and we talked about the fact that I was just having a couple people over, that there was no drinking and crap, lol.
I was a bit scared that my eyes might have been red, but I don't really get all that red-eyed so I think I lucked out. I don't think she ever knew I was high.