Why saying YOU HAD BETTER can sound scary

I've often heard non-native English speakers say something like, "You had better do it." But to a native English speaker, this sounds like a threat!

If better is a positive word, why does the pattern you had better [+ verb] seem scary?

The reason is that better is comparative (like bigger, stronger, faster, and so on). In this case, the phrase implies that your situation will be better if you do it, and we assume that if you don't do it, something bad will happen!

Here are a few examples:

  • A member of the Mafia might say, "You had better pay us." If you don't, something bad will certainly happen.
  • Your boss might say, "You had better finish this by tomorrow." Maybe she's thinking about reporting to her boss that you are under-performing, or maybe she's even thinking about firing you. 
  • My friend might say, "You had better come!" If I don't come, he might be angry or sad. He might even unfriend me on social media. 

Those previous three examples are rare. You might never hear them (especially the first one, I hope!). However, native English speakers will often say, "I had better…." This is acceptable because we can use strong language for ourselves, and because we know the consequences of our actions. Here are a couple of examples: 

  • I'd better study English (or I won't improve). 
  • I'd better go now; the last train is leaving in just a few minutes (and I don't want to miss it). 

Instead of using "you'd better," in general, just use "should." Your friend will probably say, "You should come!"

You can also simply request something politely. In the above-mentioned case of the boss, she is more likely to say, "Please finish this by tomorrow." My friend could say, "Please come!"

So, the next time you hear someone say, "You'd better...", I think you'd better be careful! 

under-performing [verb]—one's performance is not up to a certain standard. 
unfriend [verb]—removing a person from one's Friends list on Facebook (equivalent to "unfollow" on other social media platforms).