What the Hell is Rectal Prolapse?

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me: It took a while, but they finally convinced us that masturbation was evil, not only religiously but psychologically.
ah: My respect for Jews just went up another notch! Please continue.
me: They told us that circumcision would cure many illnesses and prevent many others.
ah: Logical. So enlighten me: which illnesses?
me: Standby while I read from a little book I have here... lessee... about 100 diseases or conditions including, alcoholism (eheh), ashma, syphlis, cholera, plague, gonorrhea, masturbation, eneuresis, paralysis, chorea, rectal prolapse...
ah: Rectal prolapse?!
me: Gout, feeble-mindedness, rheumatism, kidney disease, lunacy, tuberculosis...
ah: Rectal prolapse?
me: And I could go on and on, but you get the idea.
ah: What the hell is 'rectal prolapse?'