to faint, to pass out
Voy a desmayarme si no me siento.
I'm going to faint if I don't sit down.
Hacía tanto calor en el estadio que pensé que iba a desmayarme.
It was so hot in the stadium that I thought I was going to faint.
Si no los uso, mi sangre no fluye y voy a desmayarme.
If I don't use them, my blood won't flow and I'll faint.
— Intocable (2011)
I think I'm going to faint.