Tell me about it means you know that trouble only too well. Tell me about it, I have been doing it all week.
The literal reading is the opposite of the meaning, since the speaker does not want to be told anything. It is a close cousin of you're telling me.
1phrasetell me about itA way of saying you know that trouble only too well.
“He mentioned the paperwork and she groaned and said tell me about it.”
tell me about it is a phrase.
Practised in Small Talk & Everyday Phrases