tell me about it
US /tel mi əˈbaʊt ɪt/
UK /tel mi əˈbaʊt ɪt/

1.
used to express sympathy or agreement with what someone has just said, especially when they have been complaining about something
:
•
“The traffic was terrible this morning.” “Tell me about it! I was stuck for an hour.”
•
“I'm so tired of all this paperwork.” “Tell me about it, I've been doing it all week.”