Definition from Wiktionary, the free dictionary
The guideline was that British media not broadcast a phallus with a higher angle from vertical than the Mull of Kintyre peninsula.
From the shape of the Mull of Kintyre peninsula in Scotland, which somewhat resembles a flaccid penis.
Mull of Kintyre rule
- An unofficial guideline used by publishers and the media in the United Kingdom to decide to what degree of erection an image of a man's penis can be shown.