What is Cow Off?
1.
An expression of disbelief, as in "I find that extremely unlikely". A South Wales linguistic expression, especially associated with Swansea.
“I reckon Wales will beat England in the next Rugby home nations” “Cow off, they’ve got no chance."
or
“Wembley stadium should be completed in 12 months” ”Cow off, there’s enough litigation to last for the next 12 years”
See 
Random Words:
1. 
When a guy takes a shit in another guy's mouth, then proceeds to pack the shit down the poor bastard's throat with his dick un.. 
1. 
Result of a shoe being imbossed upon a dog turd.
Rick stepped on a dog fece and created a dog waffle.
See Lydia..