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.
1. MaximusBlack's Dyslexia
"Jeff I know you were trying to sound Reggae but you just went full-retard Jamackan."
Someone who adopts a fake Jamaican accent or appearance in an attempt to change their image or seem Carribean/mellow/hip/etc. This should not be confused with those who honestly accept such Jamaican qualities honestly, this term applies only to posers.
Snoop Dogg changing his name to Snoop Lion is such a Jamackan move, man.
Miss Cleo was born in LA, she's a total Jamackan.