June 12, 1978...

 "I Love Lucy"
"The Million Dollar Idea"

Original Airdate: January 11, 1954

This classic episode begins with Lucy getting "caught" with an overdrawn checking account...she informs Ethel that Ricky has cut off her allowance until June 12th.  When Ethel responds that the date is not so bad Lucy replies, June 12, 1978.