When you put bread in the toaster, walk away to get a drink, and then scream when the toast pops up and startles you.
When you make toast the next time, proceed to give yourself a pep talk reminding yourself that the toast will pop, turn around to get your drink, and still scream when the toast pops.
When you make toast again the next time, and decide to literally stand there and watch the toaster while repeating over and over that the toast will pop. Then the toast pops and scares you anyway because even within that couple minutes you started dissociating.