The tube located in a man or hermaphrodite's penis from which the white glory bursts forth, usually accompanied by grunting and or moaning sounds of pleasure.
Caleb prodded his seminal valve with a toothpick and exploded on it with his hot, sticky love juice.
Another name given to your arse, especially after a night on the beers or the day after a curry or maxican food.
"Cor, whats that smell? Is that your Clacket Valve?"
"Can you smell that? Think my Clacket Valve has rotted out."
"Smells like an old Clacket Valve in here..."
"My boss talks out his Clacket Valve."