What will happen if you take 1 percocet and 2 Tylenol pm's?

You will sleep with little or no pain, for quite a few hours :} Percocet is a pain reliever for moderate to severe pain. While beginning users report drowsiness, some chronic patients experience the opposite effect -- wakefullness. However... Tylenol PM contains a goodly dose of diphenhydramine (more often know by the brand name Benadryl); a first generation antihistimine that acts as a strong soporific -- it'll make you sleep (and without the potential dangers of other sleeping meds). The down-side is that diphenhydramine can keep you drowsy well into the next day.