Lady is going to party but can't walk in high heels shoes so she decide to ride. Unfortunately pony don't want carry lady so it will be struggle between partygirl and pony. Easy to guess who wins - pony feels partygirls angryness when she kick and slam by hand on pony's back, also jump on pony's back because she don't even think about walk to the party even she wear too short miniskirt and sexy stockings - but she don't care.
Lady was really angry because she wanted ride but stubborn pony didn't wanted carry her, just wanted go home. There were much mosquitos so lady lost her nervous and let poor pony feel that.

I understand point of pony's view, it is not nice experience to carry wild furious adult woman on back who kick and jump. BUT that is pony's job, that's why he has been bought - carry his mistress..