What it means
A casual way of admitting you have no idea, throwing your hands up at a question you can't answer. It's short, a little dismissive, the verbal shrug you give when something makes no sense and you've stopped trying to work it out.
Usage examples
"How he passed the exam without opening a book once, beats me, the lad's either a genius or very lucky."
"How he passed that exam, beats me."
"Beats me why the printer only jams on a Monday."
"Why the dog only loses its mind when the postie's early, beats me."
"Beats me how they've still not fixed that app, it's been glitching for ages."
Where it comes from
This comes from the older sense of beat meaning to baffle, puzzle, or get the better of someone. By the 19th century, if a question or problem beat you, it had you stuck. Beats me is just that idea shaved down into a quick spoken shrug for I don't know.
