I feel your pain, we went through a stage like that. I nicknamed one set of traffic lights 'poo corner' because every time without fail you would sit at the lights and hear DD doing her best work
I know what it is like to always have to do a nappy change at the most odd places and always having to arrive everywhere a few minutes early to change a nappy!
DD stopped doing it after awhile - hopefully your DS will get out of that phase soon also?