Definitions by Puffmax

Jamackan 

Noun: A fake Jamaican person or persons.

Verb: The action of talking in a fake and/or bad Jamaican accent.

Adjective: A term used to describe a very fake and/or bad Jamaican accent.

Possible sources:

1. MaximusBlack's Dyslexia

"Jeff I know you were trying to sound Reggae but you just went full-retard Jamackan."

Jamackan by Puffmax January 11, 2013