Transcription (the accent is shown in capital letters):
[s PYE-naî u rta]
Translation / meaning:
lit.: with foam around the mouth
Used when someone is eagerly trying to prove something.
More from "Russian idioms"
to get all one's strength together, to take one's courage in both hands
вот где соба́ка зары́та!
to annoy, to pester, to bore, to bother
to blame everything on somebody
to make a fool of somebody
to be free to do something
it turned out it didn't seem (popular expression)
throw aside all restraint, let oneself go