The "passion of the cut sleeve" is a traditional Chinese euphemism for male same-sex desire.
The story goes that one day Emperor Aidi was resting in the company with his favourite (read: 'lover') Dong Xian. The Emperor awoke first to find his robe's long sleeve trapped under his sleeping lover. Rather than disturb Dong Xian, he cut the sleeve off his robe.
For more on Speaking LGBT Chinese, see page 24 of the 2012 edition of Past2Present.