Beginning of 'sweetleaf' by sabbath
it's the 12", it's not on the album
there is a bit at the beginning of a track called jungle by lee perry
I'm sure there's lots of coughing in amongst the Butthole Surfers... probably a headnod in the direction of Sabbath... Sweet Loaf etc... but that's not the track i'm thinking of... i'm thinking of something on Psychic Powerless or Cream Corn I think... though i could be thinking of vomiting rather than coughing itself...