A cap for a drinking vessel, and particularly a shaker cup. The claimed cap can be securely attached to the drinking vessel or shaker cup to avoid leaks, and also includes a sealable opening through which the contents of the drinking vessel can be poured or drunk and a handle that is convenient for a user and which is attached to the cap in such a manner that the handle moves somewhat freely relative to the cap and the mechanism for closing the opening in the cap. Any non-integral components that come into contact with the contents of the vessel are easily detachable to facilitate thorough cleaning.