The phrase "blew grits" is not very common and there are not many synonyms that closely match its meaning. The phrase usually means that something has gone wrong or failed to work as intended. Synonyms that may be used in its place include "fell through," "went awry," "didn't pan out," or "failed to deliver." Any of these can be used to describe situations where plans, ideas, or expectations did not become reality or did not work out as intended. While there may not be a direct synonym for "blew grits," these alternatives can be used to convey similar meanings.