Peaking out - a phrase reffering to a state of mind, resulting from a stressful or disturbing situation, which is generally associated with an instantaneous feeling of uncertainty, paranoia and fear.
Tom: Dude, I dropped 4 tabs of acid yesterday.
Richard: Oh bro, that's a lot. How was it?
T: Dude, I was peaking out for half of it.
The time at which an ingested substance is at its highest possible concentration in the bloodstream. Used colloquially in the context of recreational drugs, most commonly psychedelics. When peaking, a psychedelic trip is usually at its most intense/powerful. The nature and duration of a peak varies by drug, user, and mindset at the time of tripping. Contrary to what some may say, it is not a term specific to any one particular drug.