Not on my bonnet, but inside.
I used to have a mk4 fiesta way back. Some squirrel thought the top of the engine was a great place to keep his stash. So there i am opening it up on the A428. I come to the black cat roundabout and release the accelerator... The car continues to accelerate WTF? Disengaged the clutch and the engine red lines... sh!t! Turned the ignition off and there goes the power assist steering and brakes!
I eventually stopped and had a look inside. The nuts had been resting on the arm that pulls the accelerator cable and when I put my foot down they had rolled down and wedged it full open. That damn squirrel almost killed me... very scary few moments!