This was a movie that was introduced to me line-by-line by Travis Pratt, a force of nature who lived on PEI during the 1980's.
"Serpentine, Shel, Serpentine!"
"There's no need to shoot at me, I'm only a dentist."
Produced in 1979, The In-laws was directed by canadian Arthur Hiller and written by Andrew Bergman but the heart of the film are the performances by its two leads: Adam Arkin and Peter Falk. To single out one over another would be a mistake. It's the two actors as a team that makes the film transcendent. Falk's son is marrying Arkin's daughter. Arkin is a nervous dentist, Falk is a unstable-seeming import-exporter... or maybe not... Arkin discovers that Falk is behind the robbery of the US Treasury and winds up "becoming inadvertently involved in a plot to defraud the US government out of millions of dollars."
It's hilarious and holds up surprising well. Rent or buy the DVD you won't regret it... Don't make the mistake of getting the 2000 remake with Micheal Douglas.