To laugh in the sleeve Meaning, Definition & Usage

Definitions
  1. or to laugh up one's sleeve , to laugh secretly, or so as not to be observed, especially while apparently preserving a grave or serious demeanor toward the person or persons laughed at.
Definitions
  1. to laugh privately or unperceived, especially while apparently preserving a grave or serious demeanor toward the person or persons laughed at; that is, perhaps, originally, by hiding the face in the wide sleeves of former times.

Webster 1913