The term HMU is an abbreviation of the words “Hit Me Up”. Just before one goes way-too-much thinking on really its right meaning, it is an important aspect to clarify on its meaning. This phrase has got no perverted or hidden meaning whatsoever.
HMU has two primary meanings
The phrase is mostly meant to mean that one is bored is is just requested his fellow friends to text him or her and or to call him or her up as well. It may also mean that one has got nothing to do and needs his or her friends to invite him or her for an activity.
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The phrase HUM happens to be a modern short-hand way of inviting a friend or friends to communicate with the specific person. It is used more often than not when the person is bored and need friends to talk to.