trip on
1. Literally, to bump into someone or something with one's foot and stumble or fall as a result. He tripped on the step running up the stairs and fell face first on the hallway. She tiptoed out of the room, trying not to trip on anyone as she left.
2. slang To experience the psychotropic effects, especially audio or visual hallucination, of some drug. Don't listen to him—he's been tripping on acid for the last three hours. We spent the weekend tripping on mushrooms while we went on hikes so we could better appreciate nature's beauty.
trip on someone or something
and trip over someone or somethingto stumble on someone or something. The place was filled with sleeping people. I tripped over perfect strangers on my way to the door. I tripped on a brick and fell into the wall.
trip on
v.1. To stumble or fall on account of hitting or catching the foot on something: I tripped on the curb and fell down on the sidewalk.
2. Slang To be under the influence of some hallucinogenic drug: He tried to write an essay while he was tripping on acid, and it made no sense at all.