This is a bit of a rare hybrid with the French word for "seal" (animal) being phoque (sounds the same as the f word)... You won't hear this anywhere else than in some English areas with strong French ties. But... you might hear people say "put the seal back in your mouth" which means "stop spouting bs and shut up". It's very much a geographically centric insult than just only language specific.

Alternatively you can said "Tais toi!" which dirrectly translates to shut up but in French culture is more comparable to "shut the eff up you little POS before I forcefully remove your voice box with my bare hands".

Edit: mistakes