SMS. It can mean several things. The first to come up in my mind is “short message service”. And when one composes a “short message” one may be tempted to abbreviate. I’m not one to go as far as to write things such as “I h8 w8ng; is CWOT” or something along the line (those proficient in text speak will probably howl with contempt at this pathetic attempt anyway), but I tend to leave the subject behind, if it is a personal pronoun. So I would for instance say “hope you had a good day”. Or “should have gone to bed early”. The context tends to do the rest. But one should not get complacent! I was in the lab, and noticed someone had left samples outside the fridge. So I put them back, and texted the guy in question “put your samples in the fridge”. Wrong! The context will not disclose if this was a subjectless sentence, or an imperative… I should pay heed. And that reminds me of a slogan I found on Facebook (yes, I am very modern): “Dear People, I don't mean to sound slutty, but feel free to use me whenever you want. Sincerely, Grammar”. Too true!