You're about as useful as a Kilkenny man with a football
Heard in Waterford
Alternative to "that's about as useful as a Kerry man with a hurl." Basically, means the topic of discussion is beyond useless.
Jaysis get yerself an iphone wudja, that oul yoke is about as useful as a Kilkenny man with a football.
Good heavens, acquire a modern telephone would you, that antiquated contraption is about as useful as a Kilkenny gentleman with a football.