1
general::
Be very eager, anxious, or impatient, as in We can't wait for the baseball season to begin or I can't wait to see Dad? it's been a year. While the literal sense of being unable to wait (for lack of time) is much older, this figurative usage dates only from about 1930.
American Heritage Idioms
2
general::
Phrase(s): can’t wait (to do something)
to be very eager, as if to be unable to endure the wait until it is possible to do something. • I’m glad it’s almost summertime—I just can’t wait to go swimming!, Phrase(s): can’t wait (for something (to happen))
to be very eager, as if to be unable to endure the wait for something to happen. • I am so eager for my birthday to come. I just can’t wait.
McGrawhill's American Idioms And Phrasal Verbs