It would be 'Bhí ádh na nÉireannach orainn' in Irish.
Ádh na nÉireannach ort / Ádh na nGael ort (singular) Ádh na nÉireannach oraibh / Ádh na nGael oraibh (plural)
Because they just do!
The Irish for 'luck' is 'ádh'
Go mbeidh an tádh leat. It bascally means may there be luck with you. It is pronounced: G'meg on taw lat.