I was once brave/dumb/foolhardy enough to slam 50 mg of Marinol (delta-9-THC) (This was back when I still played with needles.) I had also been slamming Dilaudid as well. That was the highest I've been in my life except for maybe the first time I smoked (I was able to enjoy that high without passing out.) It came on in about 10 min it seemed like, I think I may have made it an hour before passing out. I wouldn't recommend it cause it's suspended in sesame oil (It would have been fun to get a lab test of my cholesterol afterwards.) I think the experiment was kind of a waste cause all I can remember is loading up the syringe (just squirted five 10 mg pills into the back of the syringe) and being gone for a short while.
As far as natural cannabinoids I bet you could do the same thing after a simple extract to get honey oil, which I'm sure is just as bad for you. But hey, if we really gave a shit about that I don't think any of us would want to try such crazy things.