pencil me in

pencil me in

Arrange for an event or appointment with the realization it may have to be canceled or changed, as a penciled note can be erased. For example, “I don’t know for sure if I can get to your meeting, but pencil me in.” This usage, from the late 1900s, persists even though it may refer to posting on an electronic device such as an iPad rather than writing in a diary. It is becoming a cliché.
See also: pencil