I hate benadryl.
So when I saw this pop up, I was amazed that people would did it for "fun".
On the other hand, I've had it intraveneously.
Eons ago (age 13) I abused haldol. No reason, it was there, and I wanted to try. Moron. I kicked into psuedo-parkinsons (thorazine shuffle), and it would have been permanent without treatment.
2 Emergency rooms later, they gave me an IV of benadryl. I felt it go into my arm, pass through my heart, shoot up my neck, and drop my jaw. I had locked jaw that was grinding on it's own up until that point. Like I said, moron.
Then 5 seconds later it took over my brain, and the evil shivers kicked in.