The full phrase is "When in Rome, do as the Roman's do." But it has become shortened so often, some people don't get it anymore. It's an analogy making use of the strict rule of the ancient Roman empire, and synonomous with "Going with the flow," or doing something because everyone else is doing it.
"Hey, thanks for coming to my party. Do you want a beer?" Said Joe.

"When in Rome," Bob exclaimed, as he poored beer into his cup.
by JJ March 16, 2004
Get the when in rome mug.
A phrase uttered when you do something because everybody around you is doing it. shortened version of "when in Rome, do as the Romans do"

also a new wave band from the eighties, their big hit was "the promise" which can be heard in Napoleon Dynamite
I feel like something with synthesizers, pop in that When in Rome cd
by George Washington Christ December 24, 2004
Get the when in rome mug.
(phrase) When in Rome, do the Romans.
Used to describe the feeling you have when you visit a new city, and can't believe your eyes as you gaze upon hoards of beautiful women and handsome men so different from your previous girlfriends/boyfriends. This attraction may occur due to stark differences in looks, ethnicity, language, culture, clothing, or blue-balls for a long long time. By law, you are required to sleep with at least one localite to make your trip a success.
Astronaut 1: Houston, we have a problem. Alien vessel approaching ship.
Houston: You know what they say, when in rome ...
by shahifaqeer July 22, 2013
Get the when in rome mug.
Something to say when you don't understand what someone is trying to tell you. Can also mean "When in Rome, do as the Romans do" but more often people don't know what it means and say it anyway. Similar to touche
girl: you were great last night.
guy: you know, when in rome....
by korndog April 6, 2008
Get the when in rome mug.
Commonly used term, for telling someone that they should do something, or 'get on that' when they have no other explanation, and do not want to offend the poor soul. most frequently used by brunette green-eyed teenage girls.
Ex) person A:"I'm going to town for groceries, I might stop into the game on my way" Person B: "When in Rome...."
by Ballinhollabitches January 21, 2011
Get the When in Rome mug.
Used to describe a time in conversation when one would dismiss a previous comment as if to say, "I really don't care" or "I care, but whatever".
Waitress 1- "Table 32 is really being a bunch of bitches"
Waitress 2- "Well, sometimes you just have to look at yourself in the face and say 'When in Rome'".
by Fro & Erika June 10, 2008
Get the When in Rome mug.
a parody of the phrase "when in Rome, do as the Romans do", this phrase means ( used in a nice, non-belliugerent way):

"if you want to integrate into, and be a part of, polite society, behave, as a rule of thumb, like most other people of your age, gender and/or social status behave in your society in your zeitgeist"
a boy with almost no friends comes home from high school and starts conmplaining to his father:

boy: dad, why don't i have any friends my age?

father: pragmatically speaking, Brandon, I thing you are not applying correctly my famous cherry-phrase "when in Rome, speak Latin." IMHO it's doesn't take Albert einstein to figure out why you have no friends: you don't do, at least after school, what most other boys your age are doing. All you do after class is watch porn, argue with your mother and sisters as to whether or not to do your chemistry, and help Mr. and Mrs. Philips, our generous elderly neighbors, with their gardening.

boy: But that's what I have always done. Wait so you have contradicted yourself, because humans are creatureses of habit, psychologically and biologically speaking.

father (ignoring Brandon's interruption): However, most boys your age, after class, date their girlfriends, play football and maybe monkey hoops, play the saxophone or another musical instrument a la Lisa Simpson, maybe hang out with their friends and look for trouble a la Bart Simpson and Nelson Muntz, maybe even play marbles. Some young men your age even go to bars/clubs and get a refreshing drink after a hard day's work. Go and do some of the things I've mentioned and you'll make friends tic-tac-toe

boy: (imitating homer simpson): D' Oh. so no wonder then I feel and act like a white crow
by Sexydimma February 23, 2012
Get the When in Rome, speak Latin mug.