穿一条裤子

1. • to have been through thick and thin together

     of male friends

2. • to be like family
3. • to share the same view of things

Character by character

• 穿(chuān)bore through
• 一(yī)one
• 条(tiáo)strip
• 裤(kù)underpants
• 子(zi)noun suffix, as in 椅子 yǐzi "chair"