What does ‘Sod’s law’ mean?

A British axiom that boils down to the idea that: “If anything can go wrong, then it definitely will go wrong.”

“Sod’s law” is often used to explain bad luck or freakish acts of misfortune. This is more commonly known in the US as “Murphy’s law.”

“Of course my toast had to land on the floor butter-side-down. It’s Sod’s law.”