I have no idea where the horn is on my car - mind you, I have only had it 5 years 
There have been several occasions over the years when I've been 'tooted'.
Once I was waiting to go onto a small roundabout at rush hour. It was a complex junction (only a few yards away there was a second mini roundabout and 5 roads all converged together in that small area). If I had moved onto the roundabout I would have ended up blocking the traffic coming from the right which would have gridlocked the entire junction. So I waited (and waited and waited) until traffic had moved enough for me to proceed. Someone behind me (in a hurry to get home after a long day I assume) obviously felt I should have moved quicker as I was on the receiving end of several long blasts on the horn, repeated frequently until I moved.
When walking down the road I never pay attention to the bip-bip type toots - unless I'm at a junction trying to cross e.g. One time walking home from work I was 'bipped' and ignored it as usual. A work colleague the next day said - I tooted you last night to wave at you as I passed by but you didn't respond. I tried to explain to her that you don't use the horn like that but she just looked at me blankly as though she didn't have a clue what I was wittering on about!
Oh, and I've been tooted by a car that cut me up. He also "gesticulated wildly" at me. Apart from thinking 'a-hole' I ignored him - yes, it was a male driver. Needless to say, I was in the correct lane and driving to the speed limit at the time.