This sentence can be considered funny or ironic for several reasons. For one, humor often relies on surprise, and the surprise here lies in the blunt verbiarness and shock value of the sentence. The question is a sudden, candid articulation of a thought many might have privately entertained but never voiced. Hence, the outrageousness of the statement can make it humorous.
Second, the sentence's humor relies on the implied irony. The speaker paradoxically wonders how an individual who might be considered unattractive can still have multiple children, making an assumption that attractiveness is directly correlated to reproductive success. Yet, most people understand that personality, chemistry, emotional connection, timing, and many other factors often matter more in determining who ends up having children with whom - making the speaker's bewilderment amusingly naive.
Third, the humor arises from the societal expectation that 'ugly' individuals are not supposed to have such 'success'. The irony is that despite society's stereotype regarding ugliness and desirability, here is an individual who defies those norms. That contrast between what's typically expected versus what has happened creates a humorous effect.
The fourth element of humor is the sarcastic empathy it implies, where the sentence is making a harsh assessment of someone else's life choices. This reveals more about the person making the judgement than the one being judged, ironically implying a shallow perspective tied to attractiveness. The humor lies in audacity and the self-revealing nature of the judgment.
Moreover, the humor stems from the mismatch between the slang language used in the sentence and the topic it addresses. The coarse language and the urban vernacular style employed in addressing a 'taboo' topic provides a humorous contrast, suggesting a laid-back and irreverent attitude towards a somewhat sensitive subject.
Lastly, the humor in this sentence lays in its universality. It might be rude, politically incorrect, or even offensive, yet it addresses a universal concept that most people across various cultures can understand — the puzzling nature of attraction, relationships and human reproduction. It's the nerve it hits, the shared human experience it explores, that makes the sentence comical despite its blatant audacity.
YOU EVER SEE AN UGLY BITCH WITH FIVE KIDS AND BE LIKE WHO KEEPS FUCKIN YOU