I don't want to sound like a stoner, but weed is so variable these days, you might like certain strains. Going back 15 years in the UK there was only really imported hash, indoor grown indica dominant hybrids, and imported Asian outdoor weed. Most bud was some kind of Skunk No1 cross, so you always had similar effects. Then came Haze and all its sativa dominant mates, bringing anxiety etc... to certain people.
Anyway, worst experiences,
Every time I've taken Ketamine has been fairly regrettable. The first time was by far the worst. My parents were pretty liberal and my brother was having a house party. I'd been at the pub drinking and brought back a load of people. A few guys that I didn't know too well has some Ket. and in my drunken state had a fat line thinking it'll just be a bit trippy. Me and 2 other guys (A and B) we in the downstairs bathroom. A is the experienced Ket head and B has done it once. B starts grasping at a heated towe rail and wont let go, breathing really violently. Eventually he collapses out the door. My brothers mates are trainee paramedics and insist on an ambulance. I'm then stood in my garden trying to explain to my dad that I'm not on drugs. I remember his face was folding in on itself like in the Simpsons when Homer eats the worlds most sour candy at the candy expo, as I walked away into the summer house it was like I was tilting from upright to within an inch of the floor then back over to the other side. I later experienced sleep paralysis hearing my then girlfriend get it on with my then friend and not being able to get up and leave. I wasn't too bothered about it, I just didn't want to hear it.
Other ketamine adventures range from puking for hours while confused as fuck and rambling like a mad man, to laying on my bed at my own party screaming random shit and making bizarre threats towards people I hardly knew. Haha, was all fairly light hearted I suppose, I just didn't enjoy one minute of it.