Can somebody please help me by giving an English idiom or proverb equivalent for:
If everybody is doing it, I will also do it.
"When in Rome," short for "When in Rome, do as the Romans do," could work. It expresses the notion of doing what everyone else does, though it perhaps more justifies than describes such a situation.
follow the crowd: to do what everyone else is doing; go along with the majority; do what most others are doing
I am an independent thinker. I could never just follow the crowd.
When in doubt, I follow the crowd. At least I don't stand out like a fool.
jump on the bandwagon: to support something that is popular
Publishers jumped on the CD-ROM bandwagon even though they didn't know if they could sell CD-ROMs.
Consider, go with the flow and follow the herd.
go with the flow: also, go with the tide. Move along with the prevailing forces, accept the prevailing trend, as in Rather than striking out in new directions, I tend to go with the flow, or Pat isn't particularly original; she just goes with the tide. The flow in the first and more colloquial term, which dates from the late 1900s, alludes to the ebb and flow of tides and probably gained currency because of its appealing rhyme. The American Heritage® Dictionary of Idioms
: to do what most other people are doing or agree with their opinions Cambridge Dictionary of American Idioms
follow the herd: to do what other people do McMillan Dictionary
Two idioms often used in English are like lemmings and like sheep
The Cambridge Dictionary defines like lemmings as
in a silly way, without thinking, and in large numbers: People rushed like lemmings to invest in the company.
One of Oxford Dictionary Online's definition of sheep is
A person who is too easily influenced or led: the party members had become sheep, and she refused to be taken in
Both of these terms are highly negative.
Similarly, the phrases herd mentality and run with the pack suggest going along with a group, often in a blind, conforming way.
A common parental challenge to a child who wishes to do what everyone else is doing is if all your friends jumped off a bridge, would you do it too? (Uncyclopedia)
(The usual response is silence, not to be confused with agreement that the parent is correct.)
I like to say "all the cool kids are doing it"
What you're describing may be peer pressure.
Consider "Follow Suit"
- Games To play a card of the same suit as the one led.
- To do as another has done; follow an example.
You could consider Paul Simon’s line “Who am I to blow against the wind?,” but for me (and the linked Genius[dot]com annotation), “blowing against the wind” connotes more a feeling of ‘doing something that is futile’ than one of ‘doing something different from everyone else.’
However, combining the “Who am I to …” part of Simon’s line with an idiom that better captures the notion of doing the opposite of [most] other people (e.g., “go/swim against the tide” [which is, I've just noticed, the negative version of an answer already given by Elian]) would, I think, capture the notion that you’re describing:
(example of usage from ‘Confessions of an S & M Virgin’ by Linda Jaivin via Google Books)
to do the opposite of what most other people are doing It's not easy to go against the tide in defence of your principles. (sometimes + of ) He always seemed to be swimming against the tide of public opinion.
(from Cambridge Idioms Dictionary, 2nd ed. Via ‘The Free Dictionary’)
"Keeping up with the Joneses" is another way of saying it.
see this link for more information https://en.wikipedia.org/wiki/Keeping_up_with_the_Joneses
Consider "to run with the world":
to do what is popular, follow the crowd.
In addition, there's a well-known phrase "Fifty million Frenchmen can't be wrong" that can also be used to justify going along with the crowd through an appeal to majority. It can also be adapted to fit the situation, e.g. A gazillion of Elvis fans can't be wrong.
Monkey see. Monkey do! AT least, that's the one that comes to my simple mind first.
10,000,000 people can't be wrong! (Substitute 10,000,000 for whatever suitably large number you choose.) Admittedly, this can be used for other cases, where people just believe a thing, rather than do a thing, but it works that way too.
(Mind you, I believe that it's absolutely possible for 10,000,000 people to be wrong, but that's beside the point.)