This phrase is used to describe someone who is not picky or is willing to date anyone. Its literal translation is 'all the buses work for him/her', implying that the person is open to all options.
Examples
- Spanish: No entiendo por qué Juan está siempre con una chica diferente, parece que todas las micros le sirven.
- English: I don't understand why Juan is always with a different girl, it seems like he's not picky at all.