The word harass is widely misspelled and therefore shows up as a frequent typo in OPACs, on Google, and everywhere else. Harrassment alone appears 67 times in OhioLINK. The American Heritage Dictionary relates it to the word harry ("Harass and harry imply systematic persecution by besieging with repeated annoyances, threats, or demands"), which may partially explain the tendency to include an extra R when spelling harass. I find "her ass" to be a useful, if somewhat crude and perhaps ironic, mnemonic when it comes to spelling today's typo, as harassment is so often coupled with the word sexual. If you have trouble spelling this word, you might find that pronouncing it the way the British do (putting emphasis on the first syllable) will help you keep your Rs in check. And not to bug you, but also look for these forms of the word found on the Ballard list—Harrassed, Harrasses, Harrassing and Harasss*.
(Picture by Baltasar Lobo, from Platero and I: An Andalusian Elegy by Juan Ramón Jiménez. Donkey is writing the word Asnografia.)