Definition of head trip:
(n) :
(informal) A disorienting, exciting experience, especially one consisting mainly of striking sensory impressions.
(n) :
(informal) An experience or set of experiences which is intellectually challenging or stimulating.
(n) :
(informal) A state of mind in which one is distracted, disturbed, or unnerved, whether self-induced or resulting from ill-treatment by others.
(n) :
(informal) An ego trip.