níl aon tóin tinn mar do thóin thinn féin.
(there's no sore arse like your own sore arse) •
It means your own problems seem more important to you than anyone else’s.
It’s a play on words of the proverb "níl aon tinteán mar do thinteán féin" (there’s no hearth like your own hearth, or, there's no place like home)
Person A complains of something. Person B agrees and shares a similar complaint. Person A says that’s not the same thing. Person B responds, “Bhfuel, níl aon tóin tinn mar do thóin thinn féin!”