I've split the post into 2 replies as it has become way longer than intended...
The only big "oops, did not mean to consume this" moment I can remember occurred when I was living in a damp room (the ceiling had strated to collapse due to the bathroom above, and my bed got ruined in the process so I was just sleeping on the floor basically - there was no room to sleep in the living room because I'd moved a lot of my possessions there to get them out the damp, and it was already cluttered as fuck - my flatmate insisted on keeping a massive fucking wooden pallet for an arts and crafts project he never completed lol.) In hindsight, I probably would have been better off in the kitchen ha.
Anyway, I was depressed as fuck at the time and had been abusing a load of drugs - mostly masses of benzos and the RC dissociatives of the moment, the beloved diphenidine and MXP - but on this particular occasion I had finished the last of a half gram of meth and had been up the best part of 4 days. I was really pissed off at myself, because I considered my good academic record to be the only thing going for me but I had a presentation to give at 9 tomorrow and I'd spent the day pissing around with my guitar and 8 track obsessing over the intro of a song I'd just made up [it was shit btw]. So defeated and exhausted, no presentation at hand but no energy whatsoever to pull an alnighter, I took a concerned friends advice and decided to just get some sleep and wing it. I decided to have a cheeky toke to send me off, and lit up a closed pipe (cigar shaped, you couldn't see into the bowl).
Turned out it was the pipe I'd packed with 40x salvia extract on some previous evening in a moment of madness and thought better of it.
Fucking traumatic. I still shudder thinking about it even though I don't remember much specifics from the trip, I just remember the seering unwanted intensity of it.
I never did turn up for the presentation. If I did I almost certainly would have got a Masters with Distinction, but by not turning up it meant I automatically failed one of the 5 modules.
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My second time with etizolam (third with benzos in genereal..... first time I'd actually bought my own rather than a friend just giving me one or two) was similar to OP. I remember thinking "these are hardly doing shit," at first and remember taking miligram number six before complete black out. When I woke up the next day, nearly all 30 of what I had originally bought had been consumed. Kinda freaked me out at the time, but when I realised (or rather, mistakenly believed) that I could just live without social anxiety if I kept taking the little blue pills I basically ignored every warning and just sort of accepted addiction.
I can remeber at least 2 similar occasions during benzo addiction where I woke up having consumed a massive stash (one occasion, a nearly full bag of 50 diclazapam - can't remember the dosage as I never did rate them, another occasion again 50 pellets of 0.5mg clonazolam). Obviously did loads of stupid shit during those couple of years, but the one that springs to mind - probably because of your missed airplane story - is chucking out an envelope containing my passport, birth certificate and I'm pretty sure some other important document too. I knew it was in that place in my wardrobe in a brown envelope, but managed to conveniently forget while tidying my room and only realised my mistake after. It meant that basically the only work I could find without ID was distributing flyers in the town centre for some random I found through a gumtree ad.