I feel like I've always said oh instead of zero. Like if there was a zero in a phone number, or a tv channel was 104. Just easier I guess.
Yeah I sometimes slip up and say o instead of zero but it's still kinda weird that kinda thing is normal when its a number. I remember I was on the phone with a customer service rep a few months ago and when I said my callback number and used o instead of zero she was confused so I had to correct myself.