by Trey Graham, USA TODAY

Shakespeare in Love will give you the giggles even if you don't have a drama degree - though Shakespeare scholars may laugh louder and longer. Marc Norman and Tom Stoppard sprinkle their script with jokes about vain stars, showbiz rivalries and shrinks - subjects still relevant in the '90s.

Still, many of the best bits are takeoffs on lines from the Bard's plays - and there, as Hamlet would put it, is the rub. Most everyone will get the joke when the Puritan preacher Makepeace rails against "sinful" theaters in phrases lifted almost whole from Romeo and Juliet, but what about those sly references to less-familiar works? If you don't know your Cymbeline from your Coriolanus, here's a cheat sheet:

Shakespeare's signature.
Wrestling writer's block, Joseph Fiennes' Shakespeare scribbles his name over and over. Look closely: You'll see he uses different spellings - a nod to the fact that the six surviving copies of Shakespeare's signature show considerable variations in abbreviation and spelling. It's not that he couldn't remember his own name; in his era, few standardized spellings existed, even of names.

'One Gentleman.'
Fiennes says theater owner Henslowe still owes him for "one gentleman of Verona." Apparently Henslowe has paid only half the fee for The Two Gentlemen of Verona - an early Shakespeare play, and the one that catches the attention of Gwyneth Paltrow's Lady Viola with the lines she quotes for her audition: "What light is light, if Silvia be not seen?"

'The Rose smells thusly rank by any name.'
Makepeace is talking about the Rose Theatre; he concludes with, "I say a plague on both their houses." Both phrases are much like famous lines from Romeo. It's a funny moment, but an important one, too: In this early scene, Stoppard and Norman begin to show how their Shakespeare makes art of the stuff of life - the film's central idea. As the film goes on, Fiennes turns many more everyday events into high drama.

Dr. Moth.
The shrewd alchemist/shrink who ponders Shakespeare's outrageously Freudian complaints ("The proud tower of my genius has collapsed") bears the name of a smart-aleck page-boy who punctures the pretensions of his buffoonish master in Love's Labours Lost. (There's also a fairy named Moth in A Midsummer Night's Dream.)

'Master Crab is nervous. He's never played the palace.'
Not a Shakespeare gag, but one some younger audiences may not get: In vaudeville days, the Palace was a top-rank New York house; to "play the Palace," literally or figuratively, means to make it to the big time. Today's Palace is home to Broadway's Beauty and the Beast.

Rosaline's fall from grace.
Smitten by a seamstress, Fiennes changes the title of his work-in-progress Romeo and Ethel to Romeo and Rosaline. But when he catches her in bed with another, the seamstress loses her chance at immortality. Rosaline never appears onstage in the Romeo and Juliet we know, but we're told early on that she's the object of Romeo's affection. In fact, Romeo and his cohorts crash the Capulet ball chiefly because Benvolio, Mercutio and the rest want to get a better look at Rosaline; Romeo, of course, forgets her instantly when he sees Juliet.

'Give me to drink mandragora.'
A dejected Fiennes orders this potion at the local tavern. Mandragora is a sedative, and the line is from Antony and Cleopatra; the Egyptian queen, distraught that her lover has returned to Rome, tells her servant Charmian to "Give me to drink mandragora. . . . That I may sleep out this great gap of time."

Marlowe's advice.
Christopher Marlowe helps Fiennes define Romeo's character and outline the play's plot. It's funny because Marlowe is among the writers said by some doubters to be the true author of Shakespeare's plays.

That bloodthirsty kid.
A sadistic street urchin with theatrical ambitions likes Shakespeare's horrific Titus Andronicus best: "Plenty of blood - that's the only writing," he says. His name, Fiennes asks? "John Webster" - who grows up to write the morbidly violent revenge tragedy The Duchess of Malfi. Possibly the most esoteric in-joke in the film.

Marlowe's 'ghost.'
The church scene in which Lord Wessex glimpses a man he believes to be dead will remind some of the ghostly visitations in Hamlet. But Claudius, that play's murderer, never sees his victim's shade. Better parallels are Macbeth, in which Banquo's ghost appears to the usurper responsible for his death, and Julius Caesar, in which Caesar's ghost stalks Brutus on the battlefield.

'Twelfth Night.'
The play Fiennes begins at the movie's close does, indeed, feature a lead named Viola who disguises herself as a boy when shipwrecked in an unknown land. And it was commissioned - probably by Elizabeth I - for a court performance on Twelfth Night (Jan. 5, the last of the Twelve Days of Christmas). But it was written years after Romeo, and almost certainly wasn't inspired by a lost love.

The apothecary's hat.
Cast as the apothecary in the play-within-the-movie, producer Hugh Fennyman (Tom Wilkinson) fusses anxiously over wearing just the right hat. His concern comes not from pride but from a need to be part of a story that has moved him deeply, and it echoes the touching vanity of Malvolio, the major domo of Twelfth Night.

'It needs no wife come from Stratford to tell you that.'
Fiennes says this to acknowledge that he can't hope to marry Paltrow (he's already married; she's engaged to a lord). The line echoes Horatio's reply to Hamlet's observation that Denmark is full of knaves and villains: "There needs no ghost, my lord, come from the grave to tell us this."

Other Hamlet references pepper Shakespeare in Love -
some funny, some serious, too many to list. Among highlights: In a brawl, Richard Burbage gets clobbered with a skull. (The real Burbage was the first actor to play Hamlet, who delivers his "Alas, poor Yorick" speech to a skull.) Indeed, says Folger Shakespeare Library scholar Georgiana Ziegler, "As the movie moves closer and closer to tragedy you get more and more echoes of Hamlet."