They tried some kinky activities to spice up their relationship.

kinky 是形容词，由名词 kink（"弯曲、扭结"）加上形容词后缀 -y 构成。原意是"卷曲的、弯曲的"，引申为"古怪的、不寻常的"，在亲密关系中特指"非传统的、偏离常规的"亲密行为。