Romeo and Juliet/WMG
The end of the play was an Inverted "Death=Sleep" and "Sword In My Pocket" combo metaphor.
Romeo goes to the tomb and gets blitzed drunk on the "poison" (as in "What's your poison?" or "the measure makes the poison"). Juliet's kiss wakes him up, and she sheathes his knife within her... heart. Then they skip town and leave the friar to explain his knowledge of the situation, and Prince Escalus makes his heartfelt speech about the maleficence of feuds either before or after discovering the truth.
The entire "You didn't leave me any poison, perhaps I'll kiss you and see if there's any left on your lips" speech was a parody or subversion of True Love's Kiss.
Were it a genderbent fairy tale, Romeo would have woken up. Since it was Shakespeare, he didn't, and Juliet killed herself.
The Capulets and Montagues are Mafia families.
This would explain why the feuding is so heated, and why the prince (who may or may not be the Godfather in actuality) is the only one to intervene.
Benvolio orchestrated everything.
Because he is the next Montague heir in line, he plotted - possibly with Rosaline - to get Romeo to marry someone unsuitable and get disowned, so that he would inherit the Montague fortune. However, after Mercutio - the one person Benvolio truly cares about - is killed, partly because of his plotting, Benvolio decides to get revenge by orchestrating the death of everyone else.
Friar Lawrence orchestrated everything
He didn't send the letter, deliberately driving Romeo and Juliet to suicide, in order to show the families how futile their feud was.
Romeo and Juliet already knew each other.
Rosaline? Invented so that Romeo's friends wouldn't suspect him of loving a Capulet (or being gay). The conversation at the masque? Playful flirtation. Juliet's surprise at learning his identity? Sarcasm, of the "isn't playing with fire FUN?" variety. Of course, this isn't the original intent of the story, but it would be interesting to see their relationship played this way.