When used in any type of text messaging system HMU usually stands for "Hit Me Up." It means that they want you to get back to them, usually the same way they sent you the message (SMS text, Email, or Instant Message).
In 2010 FaceBook named "HMU" as the top status update trend of the year.
The HMU acronym hit the news on November 21, 2012 when three students at Apache Junction High School in Arizona were arrested for selling Hash lollipops.
Arizona.newszap.com reported that the students were using Twitter for advertising, tweeting such things as "Last chance to get Cali #HashCandy! 8-10Hr High. Gummies Lollipops Hard Candies $12 (a piece) HMU ASAP. After this week prices go up to $15!”
Tip! Text-messages are small by their nature, but clicking on the wrong one can cost you big. Here's a quick guide to help mobile security beginners avoid getting scammed shared by PCMag.com.