Quoting "T. Michael Keesey" <keesey@gmail.com>:
(And note that sometimes the "c" + front vowel combination gets slurred into a "sh": "ocean", "atrocious".)
This is a general fact about /s/ + /j/ sequences (/j/ representing the sound of the <y> in "yes"), seen also in words like "tissue" and even across word boundaries in phrases like "miss you" (which sometimes comes out rhyming with "tissue").
Similar processes apply to /z/ + /j/ (so that the sound in the middle of "Asia" is the sound at the beginning of "genre"), /d/ + /j/ (so that the first syllable of "education" sounds like the word "edge") and /t/ + /j/ (so that "got you" becomes "gotcha"). At least in my dialect.
-- **************************************************************** Nicholas J. Pharris