Poisonous Spiders in S. Africa

I was sitting around in my living room with a bunch of people having conversations with them all.  We got onto the topic of South Africa, since my friend David was from there and was with us.  There was another person who had been on a two week trip to S.A. only he had hated it.  David and I were confused by this since it was the same amazing trip that I had been on.  After he described a few strange stories of him walking down the middle of the road waving his arms in the air (among other things) we figured that he had been bitten by a poisonous spider which caused him to hallucinate the entire time he was there.