stoned to the gills
being under the influence of a drug that's so profoundly altering your state of mind that you literally have no idea what's going on or who you are. Usually associated with hallucinogens such as LSD (Acid), Psilocybin (Shrooms), PCP, DXM, and Salvia.
Man, you were stoned to the gills last night after eating that ounce of shrooms.