It's Bluto, "the champ," verses Popeye, "the sailor man," in the "fight of the century."
I think this theme - a big boxing match between these two guys - was used in a couple of other Popeye cartoons down the road, but I enjoyed this one the best. Boxing was a subject used in a lot of feature films in the 1930s and '40s. In the '30s, three sports ruled in the United States: baseball, horse racing and boxing.
Anyway, this cartoon has the insane sight gags of the '30s I enjoy where inanimate objects are anything but that, such as microphones turning into mouths and correcting each other's grammar! How about Bluto working out on a 1,000-pound iron punching bag, which he pulverizes and turns into an automobile? (Popeye did a lot of these things in these early cartoons such a punch a big fish and having it turn into hundreds of sardines. Things like that.)
The big fight, held at "Yank-Um Stadium," another pun used many times in cartoons of the '30s and '40s,
This might have been the first cartoon in which Popeye uttered a popular phrase describing himself: "I am what I am and that's all that I am!" He says that after Olive comes into his pre-fight dressing room and says if he boxes, she's going to leave him.
The boxing match, of course, was funny with some unique aspects that drew some laughs from me. Just one example: Bluto's trainer cooling him off waving a towel at his chest and the tattoo of a sailboat sailing off with the breeze. It that's kind of cartoon lunacy that makes this genre entertaining.