MBN is an acronym that stands for "must be nice". It is commonly used in text messages and social media platforms such as Twitter, Facebook, and Instagram. It can be used in several ways, such as to express envy towards someones relationship status or to show frustration towards someones situation which is seemingly better than yours. It can also be used sarcastically or in a passive-aggressive manner to express jealousy or envy. Here are some examples of how to use "MBN":

• "She told me he buys her flowers every week." "MBN!"
• "I wish I had their clothes mbn."
• "You get off work at 4? mbn."

In conclusion, MBN is a popular slang term used in informal online conversations to express a range of emotions, from genuine appreciation to sarcastic envy. The context of the conversation and the users tone will often determine the specific meaning and intention behind the use of MBN.