Shakespeare loves to put a little racy humor in a lot of his plays. The nurse in Romeo and Juliet is one of his funniest characters.
In Act 1, Scene V, after Romeo has seen Juliet for the first time, the nurse says to Romeo:
I tell you, he that can lay hold of her
Shall have the chinks.
By this she means that whoever ends up marrying Juliet will have a lot of money. That's a rather unconventional thing for this character to say.
In Act 1, Scene III, Lady Capulet talks to Juliet about marrying Paris. Juliet is less than thrilled with the idea, but the nurse seems to be excited about it. At the end of the scene she says:
Go, girl, seek happy nights to happy days.
The implication is obvious. Even though Juliet is only thirteen years old, the nurse is suggesting that Juliet will enjoy her wedding night, and nights thereafter.
The nurse's character adds humor to the tragedy,and helps propel Juliet toward Romeo. Later, the nurse opposes Juliet's relationship with Romeo, which leaves Juliet completely isolated in her desire for a life with Romeo.