Have you seen THE APARTMENT? Another great Jack Lemmon movie.
I love "The Apartment"! As good as Jack Lemmon was in it I love it because of Shirley MacLaine. IMO she was at her best then (in the late 50's/early 60's) and I had a major crush on her.
Consider her roles from that period:
"Some Came Running" - an AWESOME movie with Frank Sinatra and Dean Martin befriending the floozy, MacLaine.
"The Apartment" -
"Irma LaDouce" - she plays a prostitute to Jack Lemmon's "pimp". Hilarious!
"What a Way to Go" - an absolutely hysterical collection of boyfriends (Dean Martin, Dick van Dyke, Paul Newman, Gene Kelly and Robert Mitchum) fall by the wayside of MacLaine.