It seems it’s entirely due to the book ‘Contract Killer’ by William Hoffman and Lake Headley, which was published in 1994 and featured the word 15 times.
This is the only google books search result for ‘cocksucker’ in 1994; 1993 finds two books (with an average of 2.5 cocksuckers) while 1995 finds four books (with an average of 4).
