Screaming or howling

No dream recall last night as I was fairly intoxicated, so I thought I would share a recurring dream I used to have when I was very young. The dream would always start differently, in various places that were at least 1 floor above the ground. It would feel exactly like a normal dream (and probably would have continued normally, if left uninterrupted), and there is one occurrence that I remember more vividly than any dream I have experienced: I am in my parents bedroom with some friends from school, jumping on the bed (remember, I must have been 7 or 8 years old). Suddenly, I hear the sign that I hear in every instance of this recurring dream: footsteps up the stairs. [No doubt the sound of my parents going up to bed in the real world] I know exactly what to do at this point, as I have had years of practice: lie as flat as you can, hands by your sides, head tilted sideways. I tell my friends to do the same and they follow, apart from one. He stays standing up on the bed, and as I close my eyes I hear the door open and my friend scream as this monster throws him into a nightmare - the price to pay for not lying on the ground and therefore being invisible to him. I think I was caught by the monster a few times in the early instances of the dream, and thrown into a nightmare, and though I never remember the top half of its body, I know that the bottom half consists of the pair of 'wrong trousers' from the <PERSON> and Gromit animation. I cannot watch it now without being reminded of those nightmares.