Samuel L. Jackson's ["tagline" is actually a strategy to manage his stuttering](http://www.huffingtonpost.com/2013/06/05/samuel-l-jackson-stutter-swear_n_3389403.html). See also the scene in the King's Speech where Lionel Logue tells him to swear a whole bunch. Curse words do seem to have a unique "access method" in the brain and are often unaffected by communication disorders. I worked with delightful lady with severe aphasia in grad school who would frequently swear because it helped get the words flowing more easily.