Cat's Uncle 

A lazy person (slacker), who is laid back by nature, and unreliable in general.

Would you hire Bob to clean your gutters for you? Probably not, he can be a bit of a Cat's Uncle sometimes.
Dude my mom's new boyfriend is a real Cat's Uncle, I mean he doesn't do anything!

Cat's Uncle by Chevy Cruz February 1, 2024

uncle's cat's birthday party 

an excuse that someone uses which is most likely a lie

John: Jack didn't show up for work today. Apparently he had to go to a family gathering or something.
Jake: sounds like his uncle's cat's birthday party to me.

uncle's cat's birthday party by ja5nipe5 November 2, 2014