jill: how about we take an 11th floor tailspin for lunch?  jack: sounds like a plan
when two people involved in a workplace or office [affair] meet on the top floor of their building for a brief, but much needed, desired, and illicit midday [liaison]
"jill: how about we take an 11th floor tailspin for lunch?  jack: sounds like a plan" What is the definition of "11th floor tailspin"?