2) a particularly scary Nightmare
a Jimi Hendrix Dream is a nightmare that happens in a semi-conscious state. You are either totally asleep and dream that you are awake, but it is hard to move.
Or you are conscious but can't move because your body hasn't awoken, although your mind has.
In that state you cannot move an inch but you feel as though your spirit can, albeit with some difficulty.
This is a well known and widely accepted medical condition that most if not all humans will experience, some more frequently than others. And seems to be more common in those with known sleep problems, such as, sleepwalking, insomnia, or hypersomnia.
However being raised in a religious household your parents may confuse a Night Terror with their 2 teenage sons frequently listening to Rock Music
Kenny: Yeah, he is in the bathroom
Dads: Did he have another one of his Jimi Hendrix Dreams again last night?