A way of emphasising one's keenness to partake in an activity- often surfing, drinking or fighting.

Often shortened to mad dog.
Mad dog keen is a phrase made popular by the cult underground movie "Jordanman 2.0"
Dr Pain: "Wait...lets make this interesting. keen?"
Jordanman: "Yeah....Mad dog!"

Mayonazi: "Wanna get crunk as?"
Everyone: "fuck yeah, mad dog keen!"
by white-trash-doris May 30, 2008
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