Gonzaga College's past pupils union has hit out at drunken and offensive behaviour from a group of former pupils during their recent Leinster Senior Cup quarter-final victory.
An internal email seen by the Irish Independent was distributed to past pupils at the Jesuit school.
The email tore into "a small number of more recent past pupils" for reflecting "very poorly" on the school's past and current pupils.
"At the quarter-final match against Roscrea, there was some totally unacceptable behaviour from a small number of more recent past pupils," the email read.
"This includes extreme drunkenness, offensive banners, disrespect towards the opposition kickers, and some trouble on the streets after the game that resulted in gardaí getting involved and some arrests being made.
"Apart from the serious nature of the behaviour in itself, this reflected very poorly on Gonzaga as a school and on us as past pupils," it added.
The email even asked for some of the older members of the union to keep an eye on the offenders during next week's semi-final against Blackrock - the first time they've ever reached that stage.
Ahead of next week's semi-final, the email added: "By all means enjoy yourselves, by all means be passionate in your support of the team, but please do not arrive at the grounds in a serious state of intoxication."
The Jesuit school educated a number of well-known Irish people, including former Tánaiste Michael McDowell, Fianna Fáil justice spokesman Jim O'Callaghan, 'Sherlock' actor Andrew Scott and 'Game of Thrones' star Jack Gleeson.