SMT is one of the most abbreviation which is more that just three letters. SMT is a gateway to storytelling, connection and community. This is specialized language and chat slang used by users to communicate online. You can use SMT slang to communicate effectively and add a sense of humour to your Instagram captions, post, stories and comments. Smt means on Instagram - "Sucking my teeth", "Send me this' ' and "Smiling to myself' ' which can be applied to different ranges of situations.