When you are high (off weed) to the point that you literally keep "zoning" out. If this occurs while you are around other people, usually you will not participate in the conversation and instead sit and listen. Or not listen at all and just think. It can be very peaceful, but it can also make people wonder if you are ok and make you seem awkward.
dude i was so zoned last night that i just sat and stared for a good 20 minutes