Living with the Elderly

One evening, Dad makes one of his rare appearances at home from work and finds only his first-born child present and working on a paper.

Dad: Where's Mum?
First-born: Working at school.
Dad: Huh. Where's Bro1?
First-born: Working... downtown. As should you...?
Dad: Huh... Where's Bro2?
First-born: Working.
Dad: Eh?!
First-born: Some beer event thing. Carlsberg or Heineken, I don't remember. One of the green ones.
Dad: OH, that Guinness party issit!