Non Stop Trouble with Spies (1983)

Original title: Der Schnüffler

Herbie Melbourne is a poor schlemiel who is inadvertently caught between the Devil and the deep blue sea in this German farce about a cab driver assigned to bring a "comrade" back to the East German side of the Berlin wall, a passenger who is dead to the world, permanently, when he arrives. Herbie the cabbie is recruited by the KGB and East German Intelligence to help them discover who murdered the man in his back seat. After arriving on the West German side of the divide, Herbie is then recruited by the CIA and West German Intelligence to become a counterspy, for double what the other side is paying him. As Herbie seems to have no viable way out of this mess, he goes to a therapist for help. Reaching into her bag of tricks, she gives Herbie a small bottle he can sniff when in need of self-confidence, an act guaranteed to put him on top of any situation. Now Herbie is a cabbie, a KGB agent, a CIA agent, and a bottle sniffer -- and he is falling in love with his gorgeous therapist.