What movie are they watching?

About midway through, right after Betty loses it and burns the cookies, the Grapes are watching some old movie on TV. Looks like something from the 1940s/50s, possibly starring Peter Lawford. I want to find it and watch it.

EDIT after a few months: Anybody who doesn't help me, their mother is going to die in her sleep tonight.

EDIT 2, over one hundred years later: Man, you guys suck.