What does “tiempos de vacas flacas” mean?

Tiempos de vacas flacas means lean times — a stretch of scarcity or money trouble — set against tiempos de vacas gordas, the fat years of plenty. The image comes straight from the Bible: in Genesis, Pharaoh dreams of seven fat cows and seven thin ones, which Joseph reads as seven years of abundance followed by seven of famine. The lesson baked into the phrase: save during the fat years for the lean ones.

In the clip por la vaca flaca means roughly “because money was tight.” The expression is fully pan-Hispanic and works in any register. From the same monologue, two more Mexican-flavored gems: echarle ganas (to put your back into it, give it your all) and echarle humildad (to swallow your pride) — the resilient grit of taking any job to get through the vacas flacas.