The Nurse has sexual undertones in everything she says. She jokes that her husband made a sexual reference when Juliet was a toddler (when she has more wit she will fall upon her back).She says that women "grow by men" when they are talking about Paris' marriage proposal, which of course means that they grow in status, but also that they get pregnant.
Everything she says seems to have that sexual undercurrent to it.
When she went to arrange the marriage with Romeo, she tried to tease him by saying he had competition--not someone who loved Juliet, but someone who "would fain lay a knife aboard"--in other words, someone who wanted to have sex with her. She is a willing participant in both arranging the marriage and in arranging the ladder up to Juliet's bedroom. She is more concerned about Juliet's reputation than her actual virtue.
She talks about Romeo being honourable and virtuous in that he wants to marry Juliet, but when she hears that Romeo has killed Tybalt, she goes on a rant about how terrible men are:
There's no trust,
No faith, no honesty in men; all perjur'd,(90)
All forsworn, all naught, all dissemblers. 3.3.89-91
By this she says they are all liars, all untrustworthy and cheaters incapable of trusting or being trusted.
She also knows their value, or at least she knows the value of a good marriage for a young woman. This is why she encourages Juliet to go for the second choice and marry Paris.