In George Orwell's 1984, Hate Week is much like a Mardi Gras of public demonstrations (marches, parades) in which all of Oceania rallies for the war and for Big Brother. It is the similar to the daily Two Minutes Hate, in which the citizens rant and rave against Goldstein and the Brotherhood. It is time to get the women and children involved in arts and crafts, effigies to Big Brother himself.
Here are some examples:
...the electric current was cut off during daylight hours. It was part of the economy drive in preparation for Hate Week.
the imbecile Parsons...kept up a stream of talk about the preparations for Hate Week. He was particularly enthusiastic about a papier-mache model of Big Brother's head, two metres wide, which was being made for the occasion by his daughter's troop of Spies.
[Julia] spent an astonishing amount of time in attending lectures and demonstrations, distributing literature for the junior Anti-Sex League, preparing banners for Hate Week, making collections for the savings campaign, and such-like activities.
Overall, Hate Week is another means of control that enables the Party to further prevent their citizens from protesting against their own government. Like our media during war, Hate Week keeps its citizens focused on hating the enemy and loving its leader. Both are emblazoned in big, bright, larger-than-life effigies. The irony, of course, is that neither of them exist.