What on earth are you talking about? Course I know you.
4 seconds sound clip from the A Chump at Oxford (1939) movie soundboard.
You can hear this line at 00:52:43 in the DVD version of the movie.
Quote context
[...]
- Say, what about the trunk now?
- Good gracious, why don't you fix that window? Hit me right on the cranium.
- Your Lordship! You've got your memory back. You know me!
- What on earth are you talking about? Course I know you.
- Where's my tea and crumpets? Hurry!
- Oh, it's a miracle! A miracle!
[...]