I do this thing where I talk to myself on anything. It could be a fake interview, a character, a conversation. I was driving today and I think my friend decided to call at the same time, I don't know. I was putting my phone down and I guess I answered by accident...Damn touch-screen! I lied and said I was at home talking to my sister, but she kept laughing and asking what I was saying. I was saying "Aw, how cute! You don't have to change to be my family!" yeah I don't know, and I kept repeating it, I don't know if she heard me repeat it or if she believes me. Should I just tell her? Is this too weird? hahah
Am I gonna lose another friend to my weirdness?
Am I gonna lose another friend to my weirdness?

If she's really your friend though, she wouldn't mind. It might be a bit embarrassing for you that she heard you, but she shouldn't stop being friends with you because of it. That would just be silly.
And well I didn't mention it and yeah it's back to pretending I'm normal, I mean, normal
I'm glad things are back to "normal" for you, haha.
You've already made the excuse. If she never catches you talking to yourself again, that should erase all suspicion.
Even if knowing won't change someone's relationship with me, there are certain things that I prefer everyone to remain misinformed about and have gotten myself out of something similar like this before. (I don't talk to myself, but the method of guiding their thoughts in the wrong direction works.)
Yes I did NOT mention it again, I think she may have a feeling, but we'll just move on haha
Lol, well if it were me I'd be relieved to see someone doing the same thing as me. If we made eye contact I would even nod in agreement to what the subject was even if I didn't know--you might look at me weird, but I'd understand and also nod in agreement.