El niño perdido (1947)

If you survive the first half with his delicious absurdity, your reward is the second half, on the scenes when he teams up with his "carnal" Marcelo singing American, Cuban and Argentinian music, but ending with a very Mexican serenade. If you ever saw Jorge Negrete singing in a movie you'll laugh to tears when Tin Tan sings. And with the lighting effects, you can see actual flashes of Jorge Negrete until you hear him singing.