This. The scariest thing is when someone runs out in front of you towing on a highway. I destroyed a pair of front rotors on a pickup once because of this.
Hitting their brakes or stopping on an on-ramp.
Stopping to make a turn.
Stopping for speed bumps in stock-ride-height SUVs. I can understand in sports cars and even modern sedans, but if you're in an Expedition, you don't need to stop for the damned thing.
That's my 2nd least favorite thing. I'll never begin to understand why people think they should merge into traffic that's moving at 55+ mph by going 35mph and then hitting the brakes.