Chinese蚁居 yǐ jūTo live in crowded slum housing in expensive cities, because you can't afford the rent of a proper room.

Literally "to live like an ant". The people who live this lifestyle are called 蚁族 or “ant people”. Typically young people with low income trying to survive in a big city. They live in crowded rooms filled with bunk beds shared with 8+ roommates, where the rent is paid per bed.