Maybees don't fly in June

Maybees don't fly in June

Stop changing your mind so much. “Maybees” is a pun on “maybes,” as in “If I do X, then maybe Y will happen, but if I don't do X, then maybe Z will happen . . . I just can't decide.” When someone used to hesitate in such a fashion, someone else would be sure to pipe up with the reminder that “maybes don't fly in June.”
See also: fly, Maybe