The "official" tongue in cheek -- :-J (colon dash J)
or my variation of ;-J (semicolon dash J) or ;-j (semicolon dash j)?
I don't like the J in a serif font IMHO lower case j is better. But in a non serif font I like the upper case J. YMMV
My vote is for the ;-j (semicolon dash lower case j)