M*A*S*H - Season 3 Episode 2 Rainbow Bridge Goodbye, Farewell, and Amen.
Overview: As Hawkeye and Trapper are planning to leave for Tokyo, an unusual offer to swap POW patients between the Chinese and the 4077th comes in. Henry, after much debate, agrees to send Hawkeye, Trapper, Frank, Radar, and Klinger into enemy territory. Frank almost botches the swap when he brings a squirt gun to the exchange. Fortunately, the Chinese Dr. Lin Tam has a sense of humor; he went to the University of Illinois, after all.