NELLAS: tohle jsem potreboval:))
The joke might sound stilted at first, thanks to some archaic language.
In this case, the word "flashlight" refers not to a portable electric light but rather to an early form of flash photography. At the time this comic strip appeared in the "Wisconsin Octopus" and "Judge," photographers would ignite rapidly-burning flash powders or magnesium ribbons to produce bright bursts of artificial light. Flashbulbs were not commercially produced until the late 1920s, and electronic flash was not widely used until the late 1950s.
Language aside, the format of this comic strip seems surprisingly contemporary. As people on Twitter quickly pointed out, this "flashlight" joke is remarkably similar to a current meme that juxtaposes what you think you look like with what you actually look like. Today, the comic strip's captions would probably read something like: "What you think you look like when you take a selfie" versus "what you really look like."