It usually is irse de bruces. Maybe you found something like te vas a ir de bruces. I thing that in English it means to stumble and then land on your face.Cheers,
It could also be a warning: Be careful in this situation Ten cuidado, porque te puedes ir de bruces.
it'll be easier with more context, but "ir de bruces" presumably comes from "de bruces", what following the R. A. E. 22nd edit. dictionary comes from "de buces", that time saying "De or[igen]. inc[ierto].; c[ón]f[er]. bozo, parte inferior de la cara, con infl[uencia]. de buz, labio"
hence can be inferred that "ir de bruces [contra algo (against something)]" is similar to be falling down -or to be about to fall- with the snout, the mouth, or the nose forward, and it's used to appear metaphorically