摻沙子

1. • to mix in some sand (e.g. when making concrete)
2. • to place outsiders into a monolithic group (to infiltrate or disrupt it etc)

     fig.

Character by character

• 摻(chān)mix
• 沙(shā)surname Sha
• 子(zi)noun suffix, as in 椅子 yǐzi "chair"