What does crom a boo mean?

Answer 1

The motto of the Fitzgerald family is "Crom-a-boo", the ancient Irish war cry of the clan Fitzgerald. Crom being the name of their castle, the cry may be translated 'Crom forever!'"

Answer 2

"Crom a boo" is an Irish phrase used to show support for someone or a team, similar to saying "Go team!" or "Hooray!" It is often heard at sporting events or for encouragement.