There's like 50 shades of 'pressure' in traffic, to name just a few:

- staring angrily

- shaking fist

- various gestures involving middle finger

- shouting

- using the horn liberally

- flashing high beams

- driving really close to you

- bumping into you

- blocking you

- smash your window with something

- draw a gun

- fist fight

- etc etc

Some people also feel embarrassment by making others wait because something obvious you did.