This sentence implies humor and irony through its use of language and its provocative context, referring to both the timing of sexual activities and the individual's response to a physically threatening situation. Although, it is essential to note that comedy is subjective and depending on one's perspective, the humor and irony may or may not be apparent.
On one hand, the sentence finds humor through the juxtaposition of two, seemingly unrelated situations. The speaker discusses a physically intimate act with a woman on her menstrual cycle in the same breath as a potential conflict that's presumably reaching a climax. The abrupt shift, expressing the crude circumstances of each, can be seen as comedic through its unexpectedness and bluntness.
The humor can also rely on the idea of turning typically serious situations, such as a physical threat ('just stand there and bleed"), into a moment of levity. This can be seen as dark humor. The irony lies in the notion that an individual, instead of responding to an immediate physical threat, chooses to discuss a private sexual act. The lack of the expected reaction makes the situation humorously absurd.
Irony also comes into play here due to the role reversal implicit in the sentence. Menstruation ('on the rag') is often seen as a period of discomfort and inconvenience for the woman, and during such times a man may seek sexual favors (here referred to with slang language 'a blowey'). However, the irony is in the second part of the sentence, where the man is now seemingly in an uncomfortable and inconvenient situation, being threatened physically.
The sentence is laden with slang language and colloquialisms, which often provide elements of humor. Terms like “on the rag” and “blowey” may strike a chord of humor through their crude informalities. The fact that such terms are avoiding the literal words for the situations adds layers of humor because it points to the speaker's conversational or laid-back approach to fairly intense scenarios.
The overall humorous impact of the sentence might be considered a mode of gallows humor, or finding amusement in grim and serious situations. Gallows humor can be seen as a form of psychological release or a defensive mechanism against the harsh realities of life. Therefore, what one person finds funny or ironic about the given sentence, another person may find offensive or simply miss the humor entirely due to their own perspectives or cultural backgrounds. When she s on the rag and you re trying to get a blowey You gonna do somethin or just stand there and bleed