Oh, my giddy aunt

"Oh, my giddy aunt" is a colloquialism that is often used as an exclamation of surprise.

The Brigadier said this when he found out that Professor Rubeish was missing. (TV: The Time Warrior)

The Second Doctor said this to Dastari during an argument in the cellar. (TV: The Two Doctors)

The Second Doctor said this when surprised by a Kroton. (TV: The Krotons)

Missy said this to Clara while they are on a plane. (TV: Death in Heaven)