R' Yochanan said - R' Yishmael [the son of R' Yose's] organ was the size of a nine-kav canteen. Rav Pappa said - R' Yochanan's organ was the size of a five-kav canteen and some say that it was the size of a three-kav canteen. That of Rav Pappa himself was the size of Harpinian baskets
א"ר (אמר רבי) יוחנן איבריה דר' ישמעאל [בר' יוסי] כחמת בת תשע קבין אמר רב פפא איבריה דרבי יוחנן כחמת בת חמשת קבין ואמרי לה בת שלשת קבין דרב פפא גופיה כי דקורי דהרפנאי
A Harpinian basket holds six kavs (based on Shabbos 127 and 'תוס Tosafos ad loc 126b ד"ה מפנין however see Takanos HaShavin 48 ד"ה אבל) Tosafos 'תוס state that these comments are made by the Gemara to explain how exceedingly obese men [such as the aforementioned sages] could father children, so as to dispel any doubts concerning the genealogical fitness of their children. Chochmas Shlomo, however, suggests that the sizes of these sages' organs are to be taken allegorically, representing the sizes of their desire for intimate relations, the point being that though they were possessed of great desire ("the greater a man, the greater is his inclination [to sin]" - Succah 52), they overcame it. See also Maharal and R' Tzadok (Takanos HaShavin 47b-48a) who offer esoteric interpretations here; see also Ritva and Tos. Rabbeinu Peretz, who interpret this passage differently.
בבא מציעא פד
Bava Metzia 84