A Brief Guide to Sounding Like a Beijinger

别 (bié) is commonly used in negative imperative in standard Mandarin. In the Beijing dialect, this character is often replaced by 甭 (béng). However, the two are not semantically identical in some occasions. While 甭 sometimes resembles 不用（bùyòng), or "don't have to" in most situations, 别 is more of a petition asking someone not to do something.  The trivial semantic differences require a lot of exposure to the dialect for someone to fully understand. 

e.g. 这事您想都甭想。

     It's not possible. Don't even think about it.