What is your most horrible hallucination?

My most horrible hallucination occurred while I was in college. One night, I took some sleeping pills to help me sleep and ended up having an incredibly vivid dream that felt all too real.

I was standing alone in a white-walled room with no doors or windows, yet I could see outside – an endless expanse of desert sand dunes with a distant desert oasis far off in the horizon. Suddenly, out of nowhere, dozens of snakes appeared from the walls and began slithering around me until there were so many that all I could see were swirling snakes everywhere. Just then two giant cobras rose up above them, hissing wildly at me before rising up into the air and taking flight into the sky. As if this wasn’t scary enough already, they returned moments later with hundreds more snakes following close behind them! The sheer terror of knowing these creatures had come out of nowhere sent shivers down my body as they slowly inched closer to me until finally their heads enveloped mine entirely…

When I awoke from this terrifying nightmare still lying on my bed, it took several minutes for reality to set back in as my heart raced uncontrollably from being so scared just moments ago. After realizing it had only been a hallucination caused by the sleeping pills (which admittedly would be my last time taking such medication!) I felt grateful that none of it had actually happened but also deeply shaken by how vivid and real it seemed during those few moments when it occurred.