I get my cheese like mickey mouse, or else you better Donald duck
Cheese is slang for cash, the second half of this lyric is playing off the first using a double entendre.
One meaning being if he doesn’t get his cheese/money you’d better duck, cause he’ll be shooting.
The other is playing off the cartoon imagery of Mickey Mouse, by following up with the cartoon character best known for getting money/cheese, Donald Duck or Scrooge McDuck.
To help improve the meaning of these lyrics, visit "I Know the Future" by Lil Wayne (Ft. Mack Maine) Lyrics and leave a comment on the lyrics box