This particular scene is full of puns, particularly shown to reveal Mercutio's playful and rather bawdy personality. Many of these puns, therefore, are sexual in nature. Consider this one:
MERCUTIO: Nay, I am the very pink of courtesy.
ROMEO: Pink for flower.
Although on the surface the men are talking about courteous behavior, Mercutio actually sets Romeo up for a playful pun. The “pink flower” is here a reference to female genitalia.
They continue this pun in the following lines:
ROMEO: Why, then is my pump well flowered.
MERCUTIO: Sure wit, follow me this jest now till thou hast worn
out thy pump, that when the single sole of it is worn,
the jest may remain, after the wearing solely singular.
On the surface, Romeo counters that his shoe (or pump) is well-patterned (or flowered). The pun is that his pump (or male genitalia) has been covered in flowers (or female genitalia).
Mercutio delivers another pun later in the scene when talking to Juliet's nurse:
NURSE: Is it good e’en?
MERCUTIO: ’Tis no less, I tell you, for the bawdy hand of the
dial is now upon the prick of noon.
NURSE: Out upon you! What a man are you?
The nurse has questioned Mercutio’s use of “evening” in his greeting, and his response is laden with puns. The round dial of the clock is a pun for female genitalia, and the "prick" of the hands stand straight up at noon—a pun for an erection. Thus, the nurse scolds him for such a bawdy reply to her.