What's the meaning of "bundle of sticks up your butt" in this context?
It's from Gilmore Girls, and Lane has to go to a teenage hay ride though she thinks it's silly.
Rory says,

"I'm still fuzzy on what's fun about sitting in the cold for two hours - *with a bundle of sticks up your butt.*"

I'm not sure about the meaning of the last past of it especially because Urban dictionary says "stick up their butt" describes someone who's unpleasant.
So is she talking about people who go on a hayride? or stick here means hay?

Question

What's the meaning of "bundle of sticks up your butt" in this context?
It's from Gilmore Girls, and Lane has to go to a teenage hay ride though she thinks it's silly.
Rory says,

"I'm still fuzzy on what's fun about sitting in the cold for two hours - *with a bundle of sticks up your butt.*"

I'm not sure about the meaning of the last past of it especially because Urban dictionary says "stick up their butt" describes someone who's unpleasant. 
So is she talking about people who go on a hayride? or stick here means hay?

Answer

Sitting on hay can be uncomfortable because sitting on rough straw can for some feel like you're sitting on rough sticks. By saying '..with a bundle of sticks up your butt', she is figuratively comparing sitting on the hay (on the hay ride - usually a wagon filled with hay) with sitting on sticks that stick into your bum/behind.