Srimad Bhagavatam Canto 05, Chapter 26, Text 23

SB 5.26.23

ye tv iha vai vrsali-patayo nasta-saucacara-niyamas tyakta-lajjah pasu-caryam caranti te capi pretya puya-
vin-mutra-slesma-mala-purnarnave nipatanti tad evatibibhatsitam asnanti.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:  
The shameless husbands of lowborn sudra women live exactly like animals, and therefore they have no good behavior, cleanliness or regulated life. After death, such persons are thrown into the hell called Puyoda, where they are put into an ocean filled with pus, stool, urine, mucus, saliva and similar things. Sudras who could not improve themselves fall into that ocean and are forced to eat those disgusting things.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Srila Narottama dasa Thakura has sung,
karma-kanda, jñana-kanda, kevala visera banda,
 amrta baliya yeba khaya
nana yoni sada phire, kadarya bhaksana kare,
 tara janma adah-pate yaya
He says that persons following the paths of karma-kanda and jñana-kanda (fruitive activities and speculative thinking) are missing the opportunities for human birth and gliding down into the cycle of birth and death. Thus there is always the chance that he may be put into the Puyoda Naraka, the hell named Puyoda, where one is forced to eat stool, urine, pus, mucus, saliva and other abominable things. It is significant that this verse is spoken especially about sudras. If one is born a sudra, he must continually return to the ocean of Puyoda to eat horrible things. Thus even a born sudra is expected to become a brahmana; that is the meaning of human life. Everyone should improve himself. Krsna says in Bhagavad-gita (4.13), catur-varnyam maya srstam guna-karma-vibhagasah: “According to the three modes of material nature and the work ascribed to them, four divisions of human society were created by Me.” Even if one is by qualification a sudra, he must try to improve his position and become a brahmana. No one should try to check a person, no matter what his present position is, from coming to the platform of a brahmana or a Vaisnava. Actually, one must come to the platform of a Vaisnava. Then he automatically becomes a brahmana. This can be done only if the Krsna consciousness movement is spread, for we are trying to elevate everyone to the platform of Vaisnava. As Krsna says in Bhagavad-gita (18.66), sarva-dharman parityajya mam ekam saranam vraja: “Abandon all other duties and simply surrender unto Me.” One must give up the occupational duties of a sudra, ksatriya or vaisya and adopt the occupational duties of a Vaisnava, which include the activities of a brahmana. Krsna explains this in Bhagavad-gita (9.32):
mam hi partha vyapasritya
 ye ’pi syuh papa-yonayah
striyo vaisyas tatha sudras
 te ’pi yanti param gatim
“O son of Prtha, those who take shelter in Me, though they be of lower birth — women, vaisyas [merchants], as well as sudras [workers] — can approach the supreme destination.” Human life is specifically meant for going back home, back to Godhead. That facility should be given to everyone, whether one be a sudra, a vaisya, a woman or a ksatriya. This is the purpose of the Krsna consciousness movement. However, if one is satisfied to remain a sudra, he must suffer as described in this verse: tad evatibibhatsitam asnanti.
Srimad Bhagavatam Canto 05, Chapter 26, Text 22
Srimad Bhagavatam Canto 05, Chapter 26, Text 24