What Movie is This GIF From?

[Ash]

I saw someone using this GIF on a different forum.
What movie is it from and what exactly is going on in it?

[Rich]

That is from An American Werewolf in London and its from a dream in the movie.

[Ash]

Is it?
I've never seen all of that movie which explains why I didn't recognize it.
Thanks!

(this can be moved to the Solved section)