You must remember. Don't forget you've been well and truly laid.
2 seconds sound clip from the Dead of Night (1945) movie soundboard.
You can hear this line at 01:05:29.075 in the Blu-ray version of the movie.
Quote context
[...]
- Goodbye, old boy. Good luck. Hope you win.
- Got the passes wrong. I'd better try again.
- George.
- Yes?
- I've forgotten how to vanish.
- Look here, old man. This is shocking.
- I can get as far as this, then I can't remember what I do next.
- You must remember. Don't forget you've been well and truly laid.
- I know I've got to hold my breath and do this But then I get stuck.
- Well, what about that? No good? Well, try this
- No good. No good. Oh, I am sorry.
- It's all my fault, I'm afraid. I should've spent longer on the materialisation course.
[...]

 Dead of Night (1945)
 Dead of Night (1945)  Phantom of the Opera (1943)
 Phantom of the Opera (1943)  Scooby-Doo, Where Are You! (1969)
 Scooby-Doo, Where Are You! (1969)  Halloween III: Season of the Witch (1982)
 Halloween III: Season of the Witch (1982)  Knight Rider (1982)
 Knight Rider (1982)