Movie: Brilliantovaya ruka

Adventure, Comedy, Crime | Leonid Gayday | Soviet Union | 1969 | IMDB

The boss of a black market wants to smuggle a batch of jewelry from Turkey into the Soviet Union, by hiding it inside the orthopedic cast of a courier. Due to a mix-up, the “ordinary Soviet citizen” Semyon Gorbunkov is mistaken for the courier. When the cruise ship returns to the Soviet Union, Gorbunkov lets the militsiya know what happened, and the militsiya captain uses him as bait to catch the criminals.

I say cult classic, probably you need to be (or at least speak) Russian to fully get it.