comerse un rosco

Literally: To eat a ring-shaped pastry

Example: “Fue a la fiesta con su mejor camisa y no se comió un rosco.” — He went to the party in his best shirt and struck out completely.

English equivalent: To strike out

Origin: Traces to the traditional festivities of Madrid's San Isidro holiday in mid-May, where offering a rosquilla (a small ring-shaped pastry) to someone you wanted to dance with was a common, low-stakes way of showing romantic interest — accepting it was a good sign, and going home from the fair without having given or received one meant the evening's romantic prospects had come to nothing. A secondary, less certain theory reaches for bullfighting slang, where failing to "eat a rosca" meant a bullfighter's career failing to take off. Either way, no comerse una rosca settled into general use for any kind of failure, romantic or otherwise, and wasn't formally added to the Real Academia Española's dictionary until 1992, despite circulating in speech well before that.