Haman is a particularly vile name to Jews, symbolic with genocide, anti-semitism, and funny hats. He plays the villain in the story of Purim, a Jewish holiday which its celebrants more or less dedicate to talking about what a bastard he was while dressed up in silly costumes, eating triangular pastries (more on that later), and getting a wee bit tipsy. All in all, not a bad way to spend an evening, especially if you have to be in a synagogue. The whole story is recorded in the Megillah, one of the Jewish people's sacred texts.
According to the story, in the Hebrew Calendar Year 3405 (that's 356 BC, though at the time they didn't know it), Haman hatched a plot to wipe out all the Jews in the 127 provinces of the Persian Empire. Haman was the Prime Minister of Persia at the time, working under King Achashverosh. Pronunciations and spellings of that name differ widely, but the need to gather phlegm at the back of the throat while saying it is common to all of them, so don't be afraid to give it a shot.
Haman really had it in for a particular Jew, Mordechai, who cheesed him off by not bowing or prostrating himself in Haman's presence, which was the style of the day. He argued before the King that 'one people, scattered and divided in all provinces of His realm, whose laws are different from those of all peoples' really ought not to have the benefit of existence. The King hesitated, so Haman cooked up a long list of false accusations against the Jews, saying that they had abandoned their God, took too many days off of work for religious holidays, separated themselves from the rest of Persian society, and wouldn't be noticed if they were gone, anyway. Then, to sweeten the deal ever further, he offered to cough up 10,000 silver pieces against any financial loss the King might experience for finding his dominions Jewless. It paid off. The King handed over his signet ring, effectively giving Haman carte blanche to kill.
His first order was to have the provincial governors arm the commoners for the thirteenth of Adar, which was to be massacre day. His second was that they shouldn't tell the commoners who they were arming against until that day, by which point they would be well riled up for a bit of mass murder, and wouldn't care. They were to start with the twenty-two thousand Jewish school children that had gathered around Mordechai to pray.
Of course, too much was never enough for old Haman, and what he really wanted to see was a thoroughly dead Mordechai, for the purpose of which he constructed a fifty-cubit high gallows. Everything was going according to plan, insert diabolical laughter here.
But Haman hadn't counted on Queen Esther. The wife of the King, and a Jew herself (of this the King wasn't aware), Esther was wise to the whole scheme, and got on with some serious praying to God, who answered her prayers by filling the King in a bit during a dream. She was even willing to sacrifice her own life to save the lives of her people, for if the King found out she was Jewish, Mordechai's hanging would likely have been a double feature. She spilled it at a special banquet for Haman of her own arrangement, ratting him out in the process. Happily, he forgave her the secret when he found out what a putz Haman actually was. Mordechai was totally vindicated, and the Jews were saved. There was, however, a perfectly good gallows left standing--guess who swung from it.
How has Haman come down to us through history? With several celebratory gestures, included the making of Hamantashen, those triangular pastries, which I was always taught symbolized Haman's three-cornered hat. Noisemakers are utilized at every mention of his name during the holiday, and he has become rather well-known in Sunday school plays for his black beard and mustache. There is also, sad to say, a little song that hopefully was not taught outside my own little temple. I only remember the first verse:
The Haman Song
(Sung to the tune of BINGO)
Oh, once there was wicked man and Haman was his name-o
He had a plot to kill the Jews-he must have been insane-o!
H-A-M-A-N, H-A-M-A-N, H-A-M-A-N and Haman was his name-o!
There were others, but regrettably, they've slipped my mind.