Out in the streets, they call it merther

from Damian Marley – Welcome To Jamrock Lyrics on Rap Genius

Meaning

Merther is a word used to describe the the trance you experience when smoking cannabis while listening to reggae music.

The sample is from Ini Kamozes song World A Music. In fact, this is the whole premise of Marley’s song (it is sampled heavily, as you will hear). The line which you will hear is

Out in the streets they call it merther, when riddims spacing out your head, world a reggae music on yah-eh

Showing the lyric is merther, as defined above.
Also you can see Ini’s song is referred to as “World a Music (Out In The Streets They Call It Merther)” on his Wikipedia page.

http://www.youtube.com/watch?v=eihB9xXNRw4&t=52s

To help improve the meaning of these lyrics, visit “Welcome To Jamrock” by Damian Marley Lyrics and leave a comment on the lyrics box