Not So Secret Admirer (noun)
A cute and sometimes rather irritating way of signing a love note. If you text your S/O and sign it "NSSA", they should know it's you. If they don't, then the two of you need to have a discussion.
"I hrt u xoxoNSSA" (translation: I love you, my dearest darling. Hugs and Kisses, your S/O)