NOISE DISTURBANCE Trophy

Tap the rear touch pad to honk your horn or use the icon in the bottom left of the screen (looks like a horn) simply press either 100 times.

This is the quickest gold I have ever earned I just spammed the rear touch for a minute or two and once the trophy popped went into the settings and turned "Honk touch area" to 0%, as will annoy you big time and has no use that I can tell. And even if it does you can always use the icon.