Making Whoopee

[Joanne M. Despres]

The "behaving amorously" sense was the only one familiar to me,
for what it's worth.  I checked some recent M-W citations (from the
past 20 years or so) and found only three uses of the expression,
all of them carrying the sexual connotation.

I suppose it does strike me as a bit old-fashioned.  I associate its
use with people like the elderly Bette Davis, whose character used
the phrase in "On Golden Pond."

Joanne Despres
Merriam-Webster