I don't know anything about that - A way of saying you think they're full of hot air and you're

A way of saying you think they're full of hot air and you're not going to waste your time listening to them.

'I don't know anything about that' said when your brother said he could win the lottery every week.

'I don't know anything about that' after your friend said he could talk to aliens.

'I don't know anything about that' when your mom said she could cook a 50-course meal in 10 minutes.