Bill and Ted are called to Vice Principal Ryan's office for a meeting with their parents after they sign up for spring term classes . . . choosing only Study Hall and Girls P.E. There they learn they are to take a series of most egregiously tough classes, including Latin! They are horrified to learn that the Latin class is made up entirely of dweebs, and that their first assignment is to decipher the Latin on a rare ancient Roman coin minted for only one day in the realm of Julius Caesar. Conferring at the Circle K, they decide to go back to when the coin was made to find one. Accidentally they find themselves in Latin America instead, in the midst of an Incan rain dance ceremony. They are mistaken for rain gods and given a sumptuous banquet. All is well until they are called upon to make it rain, and when they can't the Incans attempt to boil them in oil as a sacrifice to their Sun God. The Three Most Important People send Rufus to their aid, but before he arrives the dudes are able to escape by talking the Incans into letting them make one phone call. As Bill & Ted head to Ancient Rome, Rufus finds himself the new target of the Incans' sacrifice (luckily he is later saved by the Three Most Important People). After a close call landing in the middle of a fight between two gladiators, Bill & Ted decide the best way to get the coin they need is by working for it. They are hired by a woman who needs help catering Caesar's tailgate party. They find themselves in the palace of Julius Caesar and unwittingly become the scapegoats for two evil Romans plotting to do away with Caesar by poisoning his grape juice. Spilling food on Caesar, Bill accidentally rips the man's robe trying to clean it, but the new ripped style catches on with those in attendance, leading to the first toga party. As the dudes attempt to serve Caesar his grape juice, the emperor calls for a food taster (picking out Rufus, who is in disguise as a partying Roman). It is discovered the drink is poisoned, and Rufus helps the boys escape. They are pursued by the two evil Romans, in a combination James Bond / Ben Hur style chariot race. Ducking into the Coliseum to escape their pursuers, Bill & Ted find themselves the main attractions facing a hungry lion. Rufus steps in, acting as referee, to save the dudes from being eaten. Realizing they need to save Rufus in turn, Bill & Ted hope to rain out the game by doing the Incan rain dance, which works. Bill & Ted are then captured and about to be found guilty of trying to murder Caesar when the real assassins are revealed and Bill & Ted are declared heroes instead. Caesar proclaims it Bill & Ted day and announces the minting of a one-time only, collector's item commemorative coin. Back in San Dimas, the Latin class has deciphered the front side of the coin as meaning "Let the festivities be prolonged ad infinitum", or as Bill & Ted point out, "Party On, Dudes". The dudes pass their Latin assignment by translating the flip side of the coin as "Be Excellent to Each Other".