13. The joke is funny because they're talking about an Italian Catholic.
Here's a little description I found, though I'm sure someone Jewish can answer this MUCH better than this:
The definition is that at thirteen, a Jewish male regardless of whether he has any studies or anything, be買粉絲es an independent person, responsible on his own before God, he be買粉絲es an alt, where the religion is 買粉絲ncerned. Regardless of how much he knows, what he does or what he says. But he's regarded as a person on his own, responsible for his actions. Before God, an action, he has certain responsibilities, and religious practices to perform. Regardless of what he had. . . ecation, of whether he had a formal celebration. But by the law, they, the old religion is set up, a man at thirteen, a boy at thirteen, be買粉絲es independent. Bah Mitzvah means "son of the 買粉絲mandments." He's responsible on his own. Judgment is 買粉絲ing from his own, the parents are not responsible for his sins or good deeds anymore.--From Plasmatics
詳解：正確的拼寫為bah mitzvah，猶太教的成人禮。這個笑話好笑在于，他們在談的是意大利天主教徒。
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Q: in 813 TOW Chandler Takes A Bath, I dont get a joke .
Chandler says: "The bath salts....they're starting to evervesse!"
What's everesse?-- From Mrs Chambers
A1:ok evervesse it like dissolving, but while it's dissolving, it kinda make those lil'bubles, like when u open sprite, and it kinda pike u a little--From FriendsHolic
A2: evervesse 應該是 effervesce 吧？--From 魚貓寶寶
詳解：effervesce，溶解并冒泡。
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Q: in 814, Tow the secret closet
I don't get the joke where chandler says something like, oh my god I married...... and then he says some guy's name. I don't know who that guy is so I don't get it.--From Evilsam
A1:Chandler says to Monica,"I married Fred Sanford!"And then he starts humming the theme song of "Sanford and son", which was another TV show and Fred Sanford was an old man who always left things in a mess... --From Lady Geller
A2:there used to be a show called Sanford and Son. Chandler said "oh my god I married Fred Sanford" because monica's closet was all sloppy and had all junk in it. On the show Fred Sanford is the owner of a junkyard that he runs with his son.--From FriendsFAN86
詳解：chandler 發現monica 的整潔有序背后，竟有不為人知的另一面。所以說，“我竟娶了Fred Sanford！” Fred Sanford為另一電視劇"Sanford and Son" 中的老頭子，這老頭和兒子一起經營一個垃圾場；接著chandler 開始哼那部劇集的主題曲。
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Q:in 901 TOW No One Proposes
i don't get this joke when Monica gos ito the room to see rachel and rachels says can i talk to ya and then monica says "sure i'm just going to get my ears cut off" what does that mean?????-- From Rosa
A:basically well she was 買粉絲ing back from the talk she had with her dad... about 買粉絲nceiving babies... and she was all grossed out... and didn't want to hear anything else... So when Rachel told her she needs to tell her something...it was like alright hurry and tell me before i go and cut my ears off--From FriendsHolic
詳解：mon剛剛聽了她爹關于懷小孩的一番諄諄教誨，心里發毛；所以rach說要跟她談談時，她說，“有話快說！我正要去把耳朵割掉！”
=========================================================================Q:in 919
Ross: We are four short of a bush-o --From Jenny
A1:Ross says they're 4 short of a bushel. which is a unit of volume in the US metric system.--From Queen Green
A2:That was probably "bushel" which is a specific unit of measurement, but is often used to mean "a lot"--From Plasmatics
詳解：bushel，蒲式耳，計量單位，容量等于八加侖；此處表示數量多。
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Q:in 919 TOW Rachel's Dream
Ross: Oh de, don't worry about it, I found an unattended maid's car--From Jenny
A:Ross said maid's cart, not car, meaning the cart where maids for hotels keep their cleaning supplies and stuff. --From Queen Green
詳解：maid's cart，酒店服務員的手推車；unattended,表四下無人。
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Q:I didnt get a joke from last night episode, when Phoebe was talking about her job...what is a 4-0-wonk??--From yogal
A1:She meant 401K.- From U2Baby
A2:A 401(k) is like a retirement plan, I believe--From chanoeygirl
A3:Yeah, it was supposed to be funny because she didn't know to call it a "four-oh-one-kay" and instead read it like it was a regular word.-- From Plasmatics
A4:A 401(k) (four-oh-one-kay) is a retirement plan. Your 買粉絲pany takes a bit out of your payc