In Japanese, "suki" can mean several things, but it is most commonly used as the word "like."
Sometimes it can be used as slang for the word "love" as well, since in Japanese, "daisuki" means "to like a lot."
So, If you "daisuki" something that means you like it a lot.
Japan has a lot of slang for their phrases (as do most languages), so people who slang their words, or who don't like long sentences/words don't bother to say "daisuki" would just say "suki."
Also, "suki suki" almost seems like the "cute way" to say you like something!
AND, it is NOT a blowjob; spell it RIGHT - it's SUCKY SUCKY, not SUKI SUKI. Please see Sucky! Sucky! Five Dolla!
for the right reference!!!