For modern audiences, it's easy to forget about issues of "class" in Shakespeare's famously gender-bending play. Yet, crossing gender boundaries is not the only kind of social transgression at work in Twelfth Night. The play is very much concerned with social ambition, especially as it relates to marrying above or below one's "estate" (rank). The issue is largely explored in the Malvolio plot, where the play takes particular pleasure in ridiculing Malvolio's social-climbing fantasies. Of course, Shakespeare himself was not born into a noble or even wealthy family, and famously purchased his "Gentleman" title after a lucrative theater career, which may be of interest in relation to Feste's status. While drunken fools like Sir Toby Belch eat, drink, and spend their way through life, the brilliant performer and "licensed fool," Feste, works for spare change and is often treated like a common servant.
Malvolio's elaborate fantasies about marrying Olivia are less about love than they are about his social ambition and desire for power and prestige.
While Twelfth Night seems to celebrate social upheaval like riotous partying and cross-dressing, it also ridicules ambitious attempts to cross class boundaries, which makes us question its ideas about social order.