Just Dropped In (To See What Condition My Condition Was In) was a big hit for Kenny Rogers and The First Edition in 1968, but the song was written by Mickey Newbury and I've always preferred his rendition (from the Winter Winds album). The man had a phenomenal range and feel. Incidentally it was Jimi Hendrix' favourite song and you may remember it from the Dude's dream sequence in The Big Lebowski.
Yes, this is about the tough parts of an acid trip. The Newbury version retains more of the warnings that were intended, whereas latter versions become more of a drug anthem.