The "Manning Cast" swearing bug finally reached Peyton Manning -- the Hall of Fame quarterback dropped the S-bomb live on "Monday Night Football" ... and it was hilarious!!
The Manning bros hosted their final broadcast of "MNF" for the Rams vs. Cardinals Wild Card matchup on Monday ... and just like Travis Kelce and Marshawn Lynch before him, Peyton said a dirty word.
The moment happened late in the first quarter, when Eli asked Peyton to break down a touchdown play ... but some technical issues led to a much better response.