"Get Up and Bar the Door" is a medieval ballad that presents a humorous look at domestic life.
Though it was written during the medieval period, the beginning of the poem certainly presents a scene similar to one that might be often seen in our world today: a wife working hard at her household duties and a husband sitting around giving her orders. Strong winds enter the house through the open door, and the husband tells the wife to "Gae [go] out and bar the door."
She, in summary, tells him to forget it. She's the one who is busy working, not him.
They make a pact that whoever speaks first will be the one to have to close and bar the door. They are both stubborn, and stubbornness is really what the poem is about. You could say stubbornness is the theme of the poem.
Both refuse to speak even when two strangers, both male, enter their home at midnight and eat more than is proper or appropriate. The strangers, assuming the couple can't speak, apparently assume the husband and wife are stupid and helpless, and decide that one of them should shave the husband with scalding water and the other should kiss the wife. Only then does the husband speak up to defend himself and his wife.
The wife, then, humorously, celebrates because she has won and her husband has lost--he spoke first.
Humor in the piece comes from the stubbornness of the two, as well as the wife's ignoring the fact that two strangers are violating her home, and her celebrating because she has won the petty argument with her husband.
Of course, looking at the poem with our 21st-century minds, we see a problem with the strangers assuming the couple are stupid and helpless because they can't speak. That is an obviously inaccurate assumption, of course, but probably typical of the medieval world.