Social conformance
Social conformance as a fallacy is when you push someone to agree so they fit in or don't stand out—not because the idea is actually good. Peer pressure isn't a reason to believe or decide something. The fallacy is to use "everyone else does" or "you don't want to be the only one" as an argument. The right question is whether the idea or action is correct or best, not whether it's popular.
Examples
Everyone else is voting yes—you don't want to be the only one saying no.
No one else is complaining, so why would you?
We all think that—you should too.
You'll look bad if you don't go along.
Don't rock the boat—just agree.