domingo siete

1.
SpainLatin Americaneutralinformal
- Colloquial expression meaning 'Sunday best,' i.e., one's finest clothes worn for church or special outings on Sunday.
- Used to refer to dressing up for a social occasion, often with the implication of seeking attention or making an impression.
2.
SpainLatin AmericaGeneralneutralformal
- Literal date expression meaning 'Sunday the seventh' (used to specify a particular Sunday that falls on the seventh day of a month).

Examples:

ES: - ¿Qué es domingo siete?
EN: -What's TiVo?
ES: Así no nos sorprende con tu domingo siete.
EN: We don't want to be surprised with any pregnancies.
ES: A menos que hayan salido con su domingo siete.
EN: Unless they had a slipup.
ES: ¡BATALLA POR LA VICTORIA DE ESTADOS UNIDOS! Desde el ataque no provocado y ruin de Japón el domingo siete de diciembre de 1941, existe
EN: Since the unprovoked and dastardly attack by Japan on Sunday,
ES: Hay mucha gente a la que no le gusta que sus muchachas salgan con su domingo siete. [ríe]
EN: Many people don't like it when their maids get knocked up.