Tell me about it
I can't believe how much homework we were assigned over the weekend!
|PTM||Please tell me|
|G2TU||Got to tell you|
|TTTT||To tell the truth|
|WTA||Women tell all|
|BTDTGTS||Been there, done that, got the shirt|
Most often, people use TMAI (tell me about it) as a more empathetic version of BTDT (been there, done that). Someone who sends you TMAI has likely experienced the poor situation you just described and commiserates with your plight.
However, people also use TMAI straightforwardly, to simply ask you to explain or expand upon something. For example, if you sent a text saying "ugh, my day was terrible" to your SO, and they responded with "TMAI," you can feel free to open up about your terrible day.