It is a longer version of the word sexyful, meaning exactly the same thing, but more exaggerated.
Pronouced "sh-mek-say-furl" it is twice the length of the word sexyful and every two letters in shmeksaypherll make one letter in sexyful. sh-s/me-e/ks-x/ay-y/ph-f/er-u/ll-l
Last thing I have to add. Tré Cool is the definition of shmeksaypherll! <3 Sorry, I had to say that.
Tré Cool is shmeksaypherll!
Billie Joe Armstrong is shmeksaypherll!
Mike Dirnt is shmeksaypherll!