Ordep can elaborate more since he's the one who researched and coded the Obby Oss stuff, but it's a decision and fun nice event chain (sort of like vanilla's feasts, but much nicer); it's based off a a local festival from the Cornish town of Padstow - you can see the wikipedia article here. And yes there is some variation in the events depending on if you're male or female (and your traits, too!).
If you are female, since you are a noble of high ranking, the festival planners will want to know if this year you can be considered fair game to be caught by the Oss. Should you accept there'll be events about being dragged under the cape of an Oss with one too many drinks, girls who get dragged under the cape and are taking a long time to come out... things like that 
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