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.
Generally a for name someone who wears his/her trousers too high. The name is derived from the little-known phrase "they should put some jam in their socks and invite their trousers down for dinner" the subject is then refered to as "jamsocks"
person #1 " their trousers are too high, they should put some jam in their socks and invite them down for dinner" person #2 "yup, that's jamsocks